diff --git a/Gemfile b/Gemfile
index ef6caaf..269ee33 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 source "https://rubygems.org"
 gem "authie"
 gem "autoprefixer-rails"
diff --git a/Rakefile b/Rakefile
index 9a5ea73..4237d41 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Add your own tasks in files placed in lib/tasks ending in .rake,
 # for example lib/tasks/capistrano.rake, and they will automatically be available to Rake.
 
diff --git a/api/authenticator.rb b/api/authenticator.rb
index e42b863..8c6d504 100644
--- a/api/authenticator.rb
+++ b/api/authenticator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 authenticator :server do
   friendly_name "Server Authenticator"
   header "X-Server-API-Key", "The API token for a server that you wish to authenticate with.", example: "f29a45f0d4e1744ebaee"
diff --git a/api/controllers/messages_api_controller.rb b/api/controllers/messages_api_controller.rb
index 96404ca..d362813 100644
--- a/api/controllers/messages_api_controller.rb
+++ b/api/controllers/messages_api_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 controller :messages do
   friendly_name "Messages API"
   description "This API allows you to access message details"
diff --git a/api/controllers/send_api_controller.rb b/api/controllers/send_api_controller.rb
index a51db10..5dd3164 100644
--- a/api/controllers/send_api_controller.rb
+++ b/api/controllers/send_api_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 controller :send do
   friendly_name "Send API"
   description "This API allows you to send messages"
diff --git a/api/structures/delivery_api_structure.rb b/api/structures/delivery_api_structure.rb
index d685f69..a813849 100644
--- a/api/structures/delivery_api_structure.rb
+++ b/api/structures/delivery_api_structure.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 structure :delivery do
   basic :id
   basic :status
diff --git a/api/structures/message_api_structure.rb b/api/structures/message_api_structure.rb
index 5e97e5a..8e6356b 100644
--- a/api/structures/message_api_structure.rb
+++ b/api/structures/message_api_structure.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 structure :message do
   basic :id
   basic :token
diff --git a/app/controllers/address_endpoints_controller.rb b/app/controllers/address_endpoints_controller.rb
index bd5ce72..d196875 100644
--- a/app/controllers/address_endpoints_controller.rb
+++ b/app/controllers/address_endpoints_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class AddressEndpointsController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 193a24b..2f09610 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "authie/session"
 
 class ApplicationController < ActionController::Base
diff --git a/app/controllers/concerns/within_organization.rb b/app/controllers/concerns/within_organization.rb
index 616d1c9..a918d11 100644
--- a/app/controllers/concerns/within_organization.rb
+++ b/app/controllers/concerns/within_organization.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module WithinOrganization
 
   extend ActiveSupport::Concern
diff --git a/app/controllers/credentials_controller.rb b/app/controllers/credentials_controller.rb
index 736233e..87448b7 100644
--- a/app/controllers/credentials_controller.rb
+++ b/app/controllers/credentials_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class CredentialsController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/domains_controller.rb b/app/controllers/domains_controller.rb
index c645944..dab606d 100644
--- a/app/controllers/domains_controller.rb
+++ b/app/controllers/domains_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class DomainsController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/help_controller.rb b/app/controllers/help_controller.rb
index 51d8bf0..69cff7d 100644
--- a/app/controllers/help_controller.rb
+++ b/app/controllers/help_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class HelpController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/http_endpoints_controller.rb b/app/controllers/http_endpoints_controller.rb
index 5f8558d..c3cae1b 100644
--- a/app/controllers/http_endpoints_controller.rb
+++ b/app/controllers/http_endpoints_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class HTTPEndpointsController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/ip_addresses_controller.rb b/app/controllers/ip_addresses_controller.rb
index fe00579..7a88dbf 100644
--- a/app/controllers/ip_addresses_controller.rb
+++ b/app/controllers/ip_addresses_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class IPAddressesController < ApplicationController
 
   before_action :admin_required
diff --git a/app/controllers/ip_pool_rules_controller.rb b/app/controllers/ip_pool_rules_controller.rb
index 043f004..bb30974 100644
--- a/app/controllers/ip_pool_rules_controller.rb
+++ b/app/controllers/ip_pool_rules_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class IPPoolRulesController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/ip_pools_controller.rb b/app/controllers/ip_pools_controller.rb
index d4476bf..797a9b8 100644
--- a/app/controllers/ip_pools_controller.rb
+++ b/app/controllers/ip_pools_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class IPPoolsController < ApplicationController
 
   before_action :admin_required
diff --git a/app/controllers/messages_controller.rb b/app/controllers/messages_controller.rb
index 1d267a9..0ec6b3d 100644
--- a/app/controllers/messages_controller.rb
+++ b/app/controllers/messages_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class MessagesController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/organization_ip_pools_controller.rb b/app/controllers/organization_ip_pools_controller.rb
index ace1182..125a128 100644
--- a/app/controllers/organization_ip_pools_controller.rb
+++ b/app/controllers/organization_ip_pools_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class OrganizationIPPoolsController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/organizations_controller.rb b/app/controllers/organizations_controller.rb
index 8aaebc4..bc6e863 100644
--- a/app/controllers/organizations_controller.rb
+++ b/app/controllers/organizations_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class OrganizationsController < ApplicationController
 
   before_action :admin_required, only: [:new, :create, :delete, :destroy]
diff --git a/app/controllers/routes_controller.rb b/app/controllers/routes_controller.rb
index e4c2eee..b50d5d1 100644
--- a/app/controllers/routes_controller.rb
+++ b/app/controllers/routes_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class RoutesController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/servers_controller.rb b/app/controllers/servers_controller.rb
index 8e9626b..43e8bbf 100644
--- a/app/controllers/servers_controller.rb
+++ b/app/controllers/servers_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ServersController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/sessions_controller.rb b/app/controllers/sessions_controller.rb
index 36385aa..727a61c 100644
--- a/app/controllers/sessions_controller.rb
+++ b/app/controllers/sessions_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class SessionsController < ApplicationController
 
   layout "sub"
diff --git a/app/controllers/smtp_endpoints_controller.rb b/app/controllers/smtp_endpoints_controller.rb
index cdefbcc..7671912 100644
--- a/app/controllers/smtp_endpoints_controller.rb
+++ b/app/controllers/smtp_endpoints_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class SMTPEndpointsController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/track_domains_controller.rb b/app/controllers/track_domains_controller.rb
index 31d11e2..52a41ff 100644
--- a/app/controllers/track_domains_controller.rb
+++ b/app/controllers/track_domains_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class TrackDomainsController < ApplicationController
 
   include WithinOrganization
diff --git a/app/controllers/user_controller.rb b/app/controllers/user_controller.rb
index 861c7ff..337b2be 100644
--- a/app/controllers/user_controller.rb
+++ b/app/controllers/user_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class UserController < ApplicationController
 
   skip_before_action :login_required, only: [:new, :create, :join]
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 42dbbc8..30930fe 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class UsersController < ApplicationController
 
   before_action :admin_required
diff --git a/app/controllers/webhooks_controller.rb b/app/controllers/webhooks_controller.rb
index 6b949dc..561852d 100644
--- a/app/controllers/webhooks_controller.rb
+++ b/app/controllers/webhooks_controller.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class WebhooksController < ApplicationController
 
   include WithinOrganization
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 0ddde9b..4d80ce5 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ApplicationHelper
 
   def format_delivery_details(server, text)
diff --git a/app/jobs/action_deletion_job.rb b/app/jobs/action_deletion_job.rb
index b39e877..df298e5 100644
--- a/app/jobs/action_deletion_job.rb
+++ b/app/jobs/action_deletion_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ActionDeletionJob < Postal::Job
 
   def perform
diff --git a/app/jobs/action_deletions_job.rb b/app/jobs/action_deletions_job.rb
index ebdab73..3cd2bd9 100644
--- a/app/jobs/action_deletions_job.rb
+++ b/app/jobs/action_deletions_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ActionDeletionsJob < Postal::Job
 
   def perform
diff --git a/app/jobs/check_all_dns_job.rb b/app/jobs/check_all_dns_job.rb
index 29427c5..b09f843 100644
--- a/app/jobs/check_all_dns_job.rb
+++ b/app/jobs/check_all_dns_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class CheckAllDNSJob < Postal::Job
 
   def perform
diff --git a/app/jobs/cleanup_authie_sessions_job.rb b/app/jobs/cleanup_authie_sessions_job.rb
index 6beaa36..06095eb 100644
--- a/app/jobs/cleanup_authie_sessions_job.rb
+++ b/app/jobs/cleanup_authie_sessions_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "authie/session"
 
 class CleanupAuthieSessionsJob < Postal::Job
diff --git a/app/jobs/expire_held_messages_job.rb b/app/jobs/expire_held_messages_job.rb
index a65233f..cbd560c 100644
--- a/app/jobs/expire_held_messages_job.rb
+++ b/app/jobs/expire_held_messages_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ExpireHeldMessagesJob < Postal::Job
 
   def perform
diff --git a/app/jobs/process_message_retention_job.rb b/app/jobs/process_message_retention_job.rb
index d4ab415..87a07d7 100644
--- a/app/jobs/process_message_retention_job.rb
+++ b/app/jobs/process_message_retention_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ProcessMessageRetentionJob < Postal::Job
 
   def perform
diff --git a/app/jobs/prune_suppression_lists_job.rb b/app/jobs/prune_suppression_lists_job.rb
index 772b428..004e603 100644
--- a/app/jobs/prune_suppression_lists_job.rb
+++ b/app/jobs/prune_suppression_lists_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class PruneSuppressionListsJob < Postal::Job
 
   def perform
diff --git a/app/jobs/prune_webhook_requests_job.rb b/app/jobs/prune_webhook_requests_job.rb
index 2b424cb..04bd58c 100644
--- a/app/jobs/prune_webhook_requests_job.rb
+++ b/app/jobs/prune_webhook_requests_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class PruneWebhookRequestsJob < Postal::Job
 
   def perform
diff --git a/app/jobs/requeue_webhooks_job.rb b/app/jobs/requeue_webhooks_job.rb
index 21a4684..abe13d5 100644
--- a/app/jobs/requeue_webhooks_job.rb
+++ b/app/jobs/requeue_webhooks_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class RequeueWebhooksJob < Postal::Job
 
   def perform
diff --git a/app/jobs/send_notifications_job.rb b/app/jobs/send_notifications_job.rb
index 9caf795..ac9a621 100644
--- a/app/jobs/send_notifications_job.rb
+++ b/app/jobs/send_notifications_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class SendNotificationsJob < Postal::Job
 
   def perform
diff --git a/app/jobs/send_webhook_job.rb b/app/jobs/send_webhook_job.rb
index b0a3eab..f5eadbc 100644
--- a/app/jobs/send_webhook_job.rb
+++ b/app/jobs/send_webhook_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class SendWebhookJob < Postal::Job
 
   def perform
diff --git a/app/jobs/sleep_job.rb b/app/jobs/sleep_job.rb
index 17da30c..a92d6d6 100644
--- a/app/jobs/sleep_job.rb
+++ b/app/jobs/sleep_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class SleepJob < Postal::Job
 
   def perform
diff --git a/app/jobs/tidy_raw_messages_job.rb b/app/jobs/tidy_raw_messages_job.rb
index a9654e2..cfc3f02 100644
--- a/app/jobs/tidy_raw_messages_job.rb
+++ b/app/jobs/tidy_raw_messages_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class TidyRawMessagesJob < Postal::Job
 
   def perform
diff --git a/app/jobs/unqueue_message_job.rb b/app/jobs/unqueue_message_job.rb
index a382222..9ba3085 100644
--- a/app/jobs/unqueue_message_job.rb
+++ b/app/jobs/unqueue_message_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class UnqueueMessageJob < Postal::Job
 
   def perform
diff --git a/app/jobs/webhook_delivery_job.rb b/app/jobs/webhook_delivery_job.rb
index d4217db..8c2a685 100644
--- a/app/jobs/webhook_delivery_job.rb
+++ b/app/jobs/webhook_delivery_job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class WebhookDeliveryJob < Postal::Job
 
   def perform
diff --git a/app/mailers/app_mailer.rb b/app/mailers/app_mailer.rb
index 61f366b..c2dd8cc 100644
--- a/app/mailers/app_mailer.rb
+++ b/app/mailers/app_mailer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class AppMailer < ApplicationMailer
 
   def verify_email_address(user)
diff --git a/app/mailers/application_mailer.rb b/app/mailers/application_mailer.rb
index 75864cb..bf39d80 100644
--- a/app/mailers/application_mailer.rb
+++ b/app/mailers/application_mailer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ApplicationMailer < ActionMailer::Base
 
   default from: "#{Postal.smtp_from_name} <#{Postal.smtp_from_address}>"
diff --git a/app/models/additional_route_endpoint.rb b/app/models/additional_route_endpoint.rb
index 1282d9e..b8330af 100644
--- a/app/models/additional_route_endpoint.rb
+++ b/app/models/additional_route_endpoint.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: additional_route_endpoints
diff --git a/app/models/address_endpoint.rb b/app/models/address_endpoint.rb
index d1759ac..234996f 100644
--- a/app/models/address_endpoint.rb
+++ b/app/models/address_endpoint.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: address_endpoints
diff --git a/app/models/application_record.rb b/app/models/application_record.rb
index 03c6a5b..8627f76 100644
--- a/app/models/application_record.rb
+++ b/app/models/application_record.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ApplicationRecord < ActiveRecord::Base
 
   self.abstract_class = true
diff --git a/app/models/concerns/has_authentication.rb b/app/models/concerns/has_authentication.rb
index ec60b11..c9c4b30 100644
--- a/app/models/concerns/has_authentication.rb
+++ b/app/models/concerns/has_authentication.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module HasAuthentication
 
   extend ActiveSupport::Concern
diff --git a/app/models/concerns/has_dns_checks.rb b/app/models/concerns/has_dns_checks.rb
index 920980b..13d2c9a 100644
--- a/app/models/concerns/has_dns_checks.rb
+++ b/app/models/concerns/has_dns_checks.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "resolv"
 
 module HasDNSChecks
diff --git a/app/models/concerns/has_message.rb b/app/models/concerns/has_message.rb
index 97a02a0..5e4acef 100644
--- a/app/models/concerns/has_message.rb
+++ b/app/models/concerns/has_message.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module HasMessage
 
   def self.included(base)
diff --git a/app/models/concerns/has_soft_destroy.rb b/app/models/concerns/has_soft_destroy.rb
index 7ad2865..493bbc1 100644
--- a/app/models/concerns/has_soft_destroy.rb
+++ b/app/models/concerns/has_soft_destroy.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module HasSoftDestroy
 
   def self.included(base)
diff --git a/app/models/concerns/has_uuid.rb b/app/models/concerns/has_uuid.rb
index a9b87a7..56ba5a7 100644
--- a/app/models/concerns/has_uuid.rb
+++ b/app/models/concerns/has_uuid.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module HasUUID
 
   def self.included(base)
diff --git a/app/models/credential.rb b/app/models/credential.rb
index 1a774c0..6d54421 100644
--- a/app/models/credential.rb
+++ b/app/models/credential.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: credentials
diff --git a/app/models/domain.rb b/app/models/domain.rb
index 8c35bc5..d9a3ff9 100644
--- a/app/models/domain.rb
+++ b/app/models/domain.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: domains
diff --git a/app/models/http_endpoint.rb b/app/models/http_endpoint.rb
index b87266a..5e107dd 100644
--- a/app/models/http_endpoint.rb
+++ b/app/models/http_endpoint.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: http_endpoints
diff --git a/app/models/incoming_message_prototype.rb b/app/models/incoming_message_prototype.rb
index 8dee389..0916882 100644
--- a/app/models/incoming_message_prototype.rb
+++ b/app/models/incoming_message_prototype.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class IncomingMessagePrototype
 
   attr_accessor :to
diff --git a/app/models/ip_address.rb b/app/models/ip_address.rb
index fd67e86..d6a7100 100644
--- a/app/models/ip_address.rb
+++ b/app/models/ip_address.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: ip_addresses
diff --git a/app/models/ip_pool.rb b/app/models/ip_pool.rb
index 754d87c..e0d6d20 100644
--- a/app/models/ip_pool.rb
+++ b/app/models/ip_pool.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: ip_pools
diff --git a/app/models/ip_pool_rule.rb b/app/models/ip_pool_rule.rb
index 2f37ad4..1cfa635 100644
--- a/app/models/ip_pool_rule.rb
+++ b/app/models/ip_pool_rule.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: ip_pool_rules
diff --git a/app/models/organization.rb b/app/models/organization.rb
index 1af7d7d..991a8e2 100644
--- a/app/models/organization.rb
+++ b/app/models/organization.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: organizations
diff --git a/app/models/organization_ip_pool.rb b/app/models/organization_ip_pool.rb
index 9db6f81..715323a 100644
--- a/app/models/organization_ip_pool.rb
+++ b/app/models/organization_ip_pool.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: organization_ip_pools
diff --git a/app/models/organization_user.rb b/app/models/organization_user.rb
index 3f173da..13b2789 100644
--- a/app/models/organization_user.rb
+++ b/app/models/organization_user.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: organization_users
diff --git a/app/models/outgoing_message_prototype.rb b/app/models/outgoing_message_prototype.rb
index c894917..0fd1b0b 100644
--- a/app/models/outgoing_message_prototype.rb
+++ b/app/models/outgoing_message_prototype.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "resolv"
 
 class OutgoingMessagePrototype
diff --git a/app/models/queued_message.rb b/app/models/queued_message.rb
index d0dc276..884b196 100644
--- a/app/models/queued_message.rb
+++ b/app/models/queued_message.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: queued_messages
diff --git a/app/models/route.rb b/app/models/route.rb
index 8661d50..7c49f5c 100644
--- a/app/models/route.rb
+++ b/app/models/route.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: routes
diff --git a/app/models/server.rb b/app/models/server.rb
index 506ec48..c672b3e 100644
--- a/app/models/server.rb
+++ b/app/models/server.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: servers
diff --git a/app/models/smtp_endpoint.rb b/app/models/smtp_endpoint.rb
index 5c0f094..439e283 100644
--- a/app/models/smtp_endpoint.rb
+++ b/app/models/smtp_endpoint.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: smtp_endpoints
diff --git a/app/models/statistic.rb b/app/models/statistic.rb
index 1a360f7..c7ec358 100644
--- a/app/models/statistic.rb
+++ b/app/models/statistic.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: statistics
diff --git a/app/models/track_domain.rb b/app/models/track_domain.rb
index 7108a76..d545c8e 100644
--- a/app/models/track_domain.rb
+++ b/app/models/track_domain.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: track_domains
diff --git a/app/models/user.rb b/app/models/user.rb
index ce111d1..90083b2 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: users
diff --git a/app/models/user_invite.rb b/app/models/user_invite.rb
index 35230df..92202f6 100644
--- a/app/models/user_invite.rb
+++ b/app/models/user_invite.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: user_invites
diff --git a/app/models/webhook.rb b/app/models/webhook.rb
index e5b6989..f6ccf93 100644
--- a/app/models/webhook.rb
+++ b/app/models/webhook.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: webhooks
diff --git a/app/models/webhook_event.rb b/app/models/webhook_event.rb
index 81b7252..dd20d87 100644
--- a/app/models/webhook_event.rb
+++ b/app/models/webhook_event.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: webhook_events
diff --git a/app/models/webhook_request.rb b/app/models/webhook_request.rb
index 5fc3043..5a94527 100644
--- a/app/models/webhook_request.rb
+++ b/app/models/webhook_request.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: webhook_requests
diff --git a/bin/rails b/bin/rails
index efc0377..cbfe38b 100755
--- a/bin/rails
+++ b/bin/rails
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 APP_PATH = File.expand_path("../config/application", __dir__)
 require_relative "../config/boot"
 require "rails/commands"
diff --git a/bin/rake b/bin/rake
index 4fbf10b..d648cf0 100755
--- a/bin/rake
+++ b/bin/rake
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 require_relative "../config/boot"
 require "rake"
 Rake.application.run
diff --git a/bin/setup b/bin/setup
index 37be32e..f216f6f 100755
--- a/bin/setup
+++ b/bin/setup
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 require "pathname"
 require "fileutils"
 include FileUtils
diff --git a/bin/update b/bin/update
index db28935..31499ea 100755
--- a/bin/update
+++ b/bin/update
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 require "pathname"
 require "fileutils"
 include FileUtils
diff --git a/config.ru b/config.ru
index 826d2c9..2e2c5e2 100644
--- a/config.ru
+++ b/config.ru
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This file is used by Rack-based servers to start the application.
 
 require_relative "config/environment"
diff --git a/config/application.rb b/config/application.rb
index 3361592..bebd5c7 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "boot"
 
 require "rails"
diff --git a/config/boot.rb b/config/boot.rb
index 6a4545b..37023fe 100644
--- a/config/boot.rb
+++ b/config/boot.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../Gemfile", __dir__)
 
 $stdout.sync = true
diff --git a/config/cron.rb b/config/cron.rb
index b9def94..2d7e6f9 100644
--- a/config/cron.rb
+++ b/config/cron.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Clockwork
 
   configure do |config|
diff --git a/config/environment.rb b/config/environment.rb
index cac5315..a21c0c5 100644
--- a/config/environment.rb
+++ b/config/environment.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Load the Rails application.
 require_relative "application"
 
diff --git a/config/environments/development.rb b/config/environments/development.rb
index c3e7b0a..f556ed8 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
diff --git a/config/environments/production.rb b/config/environments/production.rb
index 8c12538..40ba9d3 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
diff --git a/config/environments/test.rb b/config/environments/test.rb
index a3a92fb..be3dbc5 100644
--- a/config/environments/test.rb
+++ b/config/environments/test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
diff --git a/config/initializers/application_controller_renderer.rb b/config/initializers/application_controller_renderer.rb
index 51639b6..315ac48 100644
--- a/config/initializers/application_controller_renderer.rb
+++ b/config/initializers/application_controller_renderer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # ApplicationController.renderer.defaults.merge!(
diff --git a/config/initializers/assets.rb b/config/initializers/assets.rb
index 0838ada..b4e1da0 100644
--- a/config/initializers/assets.rb
+++ b/config/initializers/assets.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # Version of your assets, change this if you want to expire all your assets.
diff --git a/config/initializers/backtrace_silencers.rb b/config/initializers/backtrace_silencers.rb
index 59385cd..d0f0d3b 100644
--- a/config/initializers/backtrace_silencers.rb
+++ b/config/initializers/backtrace_silencers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # You can add backtrace silencers for libraries that you're using but don't wish to see in your backtraces.
diff --git a/config/initializers/cookies_serializer.rb b/config/initializers/cookies_serializer.rb
index 5a6a32d..2a72959 100644
--- a/config/initializers/cookies_serializer.rb
+++ b/config/initializers/cookies_serializer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # Specify a serializer for the signed and encrypted cookie jars.
diff --git a/config/initializers/filter_parameter_logging.rb b/config/initializers/filter_parameter_logging.rb
index 4a994e1..b7fe123 100644
--- a/config/initializers/filter_parameter_logging.rb
+++ b/config/initializers/filter_parameter_logging.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # Configure sensitive parameters which will be filtered from the log file.
diff --git a/config/initializers/inflections.rb b/config/initializers/inflections.rb
index 0185b3b..82b9949 100644
--- a/config/initializers/inflections.rb
+++ b/config/initializers/inflections.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # Add new inflection rules using the following format. Inflections
diff --git a/config/initializers/mail_extensions.rb b/config/initializers/mail_extensions.rb
index e51e364..20a6cc6 100644
--- a/config/initializers/mail_extensions.rb
+++ b/config/initializers/mail_extensions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "mail"
 module Mail
 
diff --git a/config/initializers/mime_types.rb b/config/initializers/mime_types.rb
index dc18996..6e1d16f 100644
--- a/config/initializers/mime_types.rb
+++ b/config/initializers/mime_types.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # Add new mime types for use in respond_to blocks:
diff --git a/config/initializers/new_framework_defaults.rb b/config/initializers/new_framework_defaults.rb
index 761ff37..28e0e3b 100644
--- a/config/initializers/new_framework_defaults.rb
+++ b/config/initializers/new_framework_defaults.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 #
 # This file contains migration options to ease your Rails 5.0 upgrade.
diff --git a/config/initializers/postal.rb b/config/initializers/postal.rb
index e5cfc9f..5acc334 100644
--- a/config/initializers/postal.rb
+++ b/config/initializers/postal.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 require "postal"
diff --git a/config/initializers/record_key_for_dom.rb b/config/initializers/record_key_for_dom.rb
index b9ff469..41e4668 100644
--- a/config/initializers/record_key_for_dom.rb
+++ b/config/initializers/record_key_for_dom.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActionView
   module RecordIdentifier
 
diff --git a/config/initializers/secret_key.rb b/config/initializers/secret_key.rb
index b649767..bd4df02 100644
--- a/config/initializers/secret_key.rb
+++ b/config/initializers/secret_key.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 if Postal.config.rails&.secret_key
   Rails.application.secrets.secret_key_base = Postal.config.rails.secret_key
 else
diff --git a/config/initializers/secure_headers.rb b/config/initializers/secure_headers.rb
index 98422c8..36b7227 100644
--- a/config/initializers/secure_headers.rb
+++ b/config/initializers/secure_headers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 SecureHeaders::Configuration.default do |config|
   config.hsts = SecureHeaders::OPT_OUT
 
diff --git a/config/initializers/sentry.rb b/config/initializers/sentry.rb
index 22b6731..ec4390c 100644
--- a/config/initializers/sentry.rb
+++ b/config/initializers/sentry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "postal/config"
 
 if Postal.config.general&.exception_url
diff --git a/config/initializers/session_store.rb b/config/initializers/session_store.rb
index d5ee351..7c8845e 100644
--- a/config/initializers/session_store.rb
+++ b/config/initializers/session_store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 Rails.application.config.session_store :cookie_store, key: "_postal_session"
diff --git a/config/initializers/smtp.rb b/config/initializers/smtp.rb
index 9380825..b0c616b 100644
--- a/config/initializers/smtp.rb
+++ b/config/initializers/smtp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "postal/config"
 if Postal.config&.smtp
   ActionMailer::Base.delivery_method = :smtp
diff --git a/config/initializers/smtp_extensions.rb b/config/initializers/smtp_extensions.rb
index 609560f..7a6a2d9 100644
--- a/config/initializers/smtp_extensions.rb
+++ b/config/initializers/smtp_extensions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Net::SMTP::Response
 
   def message
diff --git a/config/initializers/trusted_proxies.rb b/config/initializers/trusted_proxies.rb
index c4317e6..651e5cb 100644
--- a/config/initializers/trusted_proxies.rb
+++ b/config/initializers/trusted_proxies.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Rack
   class Request
 
diff --git a/config/initializers/wrap_parameters.rb b/config/initializers/wrap_parameters.rb
index bbfc396..18c3825 100644
--- a/config/initializers/wrap_parameters.rb
+++ b/config/initializers/wrap_parameters.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # This file contains settings for ActionController::ParamsWrapper which
diff --git a/config/initializers/zeitwerk.rb b/config/initializers/zeitwerk.rb
index 91562a1..2c80862 100644
--- a/config/initializers/zeitwerk.rb
+++ b/config/initializers/zeitwerk.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 Rails.autoloaders.each do |autoloader|
   # Ignore the message DB migrations directory as it doesn't follow
   # Zeitwerk's conventions and is always loaded and executed in order.
diff --git a/config/puma.rb b/config/puma.rb
index 98e3877..148bba9 100644
--- a/config/puma.rb
+++ b/config/puma.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../lib/postal/config"
 threads_count = Postal.config.web_server&.max_threads&.to_i || 5
 threads         threads_count, threads_count
diff --git a/config/routes.rb b/config/routes.rb
index 48877e8..82ba97f 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 Rails.application.routes.draw do
   scope "org/:org_permalink", as: "organization" do
     resources :domains, only: [:index, :new, :create, :destroy] do
diff --git a/db/migrate/20161003195209_create_authie_sessions.authie.rb b/db/migrate/20161003195209_create_authie_sessions.authie.rb
index 4b41180..0a6d7d5 100644
--- a/db/migrate/20161003195209_create_authie_sessions.authie.rb
+++ b/db/migrate/20161003195209_create_authie_sessions.authie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This migration comes from authie (originally 20141012174250)
 class CreateAuthieSessions < ActiveRecord::Migration
 
diff --git a/db/migrate/20161003195210_add_indexes_to_authie_sessions.authie.rb b/db/migrate/20161003195210_add_indexes_to_authie_sessions.authie.rb
index 38a25ee..bfbc714 100644
--- a/db/migrate/20161003195210_add_indexes_to_authie_sessions.authie.rb
+++ b/db/migrate/20161003195210_add_indexes_to_authie_sessions.authie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This migration comes from authie (originally 20141013115205)
 class AddIndexesToAuthieSessions < ActiveRecord::Migration
 
diff --git a/db/migrate/20161003195211_add_parent_id_to_authie_sessions.authie.rb b/db/migrate/20161003195211_add_parent_id_to_authie_sessions.authie.rb
index 674dff8..d28b3fa 100644
--- a/db/migrate/20161003195211_add_parent_id_to_authie_sessions.authie.rb
+++ b/db/migrate/20161003195211_add_parent_id_to_authie_sessions.authie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This migration comes from authie (originally 20150109144120)
 class AddParentIdToAuthieSessions < ActiveRecord::Migration
 
diff --git a/db/migrate/20161003195212_add_two_factor_auth_fields_to_authie.authie.rb b/db/migrate/20161003195212_add_two_factor_auth_fields_to_authie.authie.rb
index f1204b1..709e552 100644
--- a/db/migrate/20161003195212_add_two_factor_auth_fields_to_authie.authie.rb
+++ b/db/migrate/20161003195212_add_two_factor_auth_fields_to_authie.authie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This migration comes from authie (originally 20150305135400)
 class AddTwoFactorAuthFieldsToAuthie < ActiveRecord::Migration
 
diff --git a/db/migrate/20170418200606_initial_schema.rb b/db/migrate/20170418200606_initial_schema.rb
index 2d42ff1..f3a7fc6 100644
--- a/db/migrate/20170418200606_initial_schema.rb
+++ b/db/migrate/20170418200606_initial_schema.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class InitialSchema < ActiveRecord::Migration
 
   def up
diff --git a/db/migrate/20170421195414_add_token_hashes_to_authie_sessions.authie.rb b/db/migrate/20170421195414_add_token_hashes_to_authie_sessions.authie.rb
index fc23ed9..e6e90d0 100644
--- a/db/migrate/20170421195414_add_token_hashes_to_authie_sessions.authie.rb
+++ b/db/migrate/20170421195414_add_token_hashes_to_authie_sessions.authie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This migration comes from authie (originally 20170417170000)
 class AddTokenHashesToAuthieSessions < ActiveRecord::Migration
 
diff --git a/db/migrate/20170421195415_add_index_to_token_hashes_on_authie_sessions.authie.rb b/db/migrate/20170421195415_add_index_to_token_hashes_on_authie_sessions.authie.rb
index 362c52a..1aeae15 100644
--- a/db/migrate/20170421195415_add_index_to_token_hashes_on_authie_sessions.authie.rb
+++ b/db/migrate/20170421195415_add_index_to_token_hashes_on_authie_sessions.authie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This migration comes from authie (originally 20170421174100)
 class AddIndexToTokenHashesOnAuthieSessions < ActiveRecord::Migration
 
diff --git a/db/migrate/20170428153353_remove_type_from_ip_pools.rb b/db/migrate/20170428153353_remove_type_from_ip_pools.rb
index 40a9b18..bbba554 100644
--- a/db/migrate/20170428153353_remove_type_from_ip_pools.rb
+++ b/db/migrate/20170428153353_remove_type_from_ip_pools.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class RemoveTypeFromIPPools < ActiveRecord::Migration[5.0]
 
   def change
diff --git a/db/migrate/20180216114344_add_host_to_authie_sessions.authie.rb b/db/migrate/20180216114344_add_host_to_authie_sessions.authie.rb
index df6bef7..3c12d3c 100644
--- a/db/migrate/20180216114344_add_host_to_authie_sessions.authie.rb
+++ b/db/migrate/20180216114344_add_host_to_authie_sessions.authie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This migration comes from authie (originally 20180215152200)
 class AddHostToAuthieSessions < ActiveRecord::Migration[4.2]
 
diff --git a/db/migrate/20200717083943_add_uuid_to_credentials.rb b/db/migrate/20200717083943_add_uuid_to_credentials.rb
index efcb6d2..6952555 100644
--- a/db/migrate/20200717083943_add_uuid_to_credentials.rb
+++ b/db/migrate/20200717083943_add_uuid_to_credentials.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class AddUUIDToCredentials < ActiveRecord::Migration[5.2]
 
   def change
diff --git a/db/migrate/20210727210551_add_priority_to_ip_addresses.rb b/db/migrate/20210727210551_add_priority_to_ip_addresses.rb
index eae5cd7..74589a9 100644
--- a/db/migrate/20210727210551_add_priority_to_ip_addresses.rb
+++ b/db/migrate/20210727210551_add_priority_to_ip_addresses.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class AddPriorityToIPAddresses < ActiveRecord::Migration[5.2]
 
   def change
diff --git a/db/migrate/20240206173036_add_privacy_mode_to_servers.rb b/db/migrate/20240206173036_add_privacy_mode_to_servers.rb
index 7757219..cb1843a 100644
--- a/db/migrate/20240206173036_add_privacy_mode_to_servers.rb
+++ b/db/migrate/20240206173036_add_privacy_mode_to_servers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class AddPrivacyModeToServers < ActiveRecord::Migration[6.1]
   def change
     add_column :servers, :privacy_mode, :boolean, default: false
diff --git a/db/schema.rb b/db/schema.rb
index a1b9e76..2875275 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This file is auto-generated from the current state of the database. Instead
 # of editing this file, please use the migrations feature of Active Record to
 # incrementally modify your database, and then regenerate this schema definition.
diff --git a/lib/postal.rb b/lib/postal.rb
index b6f261b..dac6e7e 100644
--- a/lib/postal.rb
+++ b/lib/postal.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 module Postal
 end
diff --git a/lib/postal/app_logger.rb b/lib/postal/app_logger.rb
index 4bac388..d0be66d 100644
--- a/lib/postal/app_logger.rb
+++ b/lib/postal/app_logger.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "logger"
 
 module Postal
diff --git a/lib/postal/bounce_message.rb b/lib/postal/bounce_message.rb
index 4c12a29..31136fb 100644
--- a/lib/postal/bounce_message.rb
+++ b/lib/postal/bounce_message.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class BounceMessage
 
diff --git a/lib/postal/config.rb b/lib/postal/config.rb
index 3b9c9e4..b86e84b 100644
--- a/lib/postal/config.rb
+++ b/lib/postal/config.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "erb"
 require "yaml"
 require "pathname"
diff --git a/lib/postal/countries.rb b/lib/postal/countries.rb
index 0eeb4e3..308cc93 100644
--- a/lib/postal/countries.rb
+++ b/lib/postal/countries.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module Countries
 
diff --git a/lib/postal/dkim_header.rb b/lib/postal/dkim_header.rb
index 60f81d5..d9206c3 100644
--- a/lib/postal/dkim_header.rb
+++ b/lib/postal/dkim_header.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class DKIMHeader
 
diff --git a/lib/postal/error.rb b/lib/postal/error.rb
index d00a423..2c4fa88 100644
--- a/lib/postal/error.rb
+++ b/lib/postal/error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
 
   module Errors
diff --git a/lib/postal/helpers.rb b/lib/postal/helpers.rb
index e4b7262..f2d8f0f 100644
--- a/lib/postal/helpers.rb
+++ b/lib/postal/helpers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module Helpers
 
diff --git a/lib/postal/http.rb b/lib/postal/http.rb
index a3d1399..4b9393b 100644
--- a/lib/postal/http.rb
+++ b/lib/postal/http.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "net/https"
 require "uri"
 
diff --git a/lib/postal/http_sender.rb b/lib/postal/http_sender.rb
index c6a23ee..158ffc0 100644
--- a/lib/postal/http_sender.rb
+++ b/lib/postal/http_sender.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class HTTPSender < Sender
 
diff --git a/lib/postal/job.rb b/lib/postal/job.rb
index 56b872e..7845145 100644
--- a/lib/postal/job.rb
+++ b/lib/postal/job.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "nifty/utils/random_string"
 
 module Postal
diff --git a/lib/postal/message_db.rb b/lib/postal/message_db.rb
index dcc50bc..ac46b5f 100644
--- a/lib/postal/message_db.rb
+++ b/lib/postal/message_db.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
   end
diff --git a/lib/postal/message_db/click.rb b/lib/postal/message_db/click.rb
index b476e4b..0de25e2 100644
--- a/lib/postal/message_db/click.rb
+++ b/lib/postal/message_db/click.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class Click
diff --git a/lib/postal/message_db/connection_pool.rb b/lib/postal/message_db/connection_pool.rb
index 579349c..7cbb3b2 100644
--- a/lib/postal/message_db/connection_pool.rb
+++ b/lib/postal/message_db/connection_pool.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class ConnectionPool
diff --git a/lib/postal/message_db/database.rb b/lib/postal/message_db/database.rb
index ad9f26e..5e2ab5c 100644
--- a/lib/postal/message_db/database.rb
+++ b/lib/postal/message_db/database.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class Database
@@ -144,7 +145,7 @@ module Postal
       #   :count     => Return a count of the results instead of the actual data
       #
       def select(table, options = {})
-        sql_query = "SELECT"
+        sql_query = String.new("SELECT")
         if options[:count]
           sql_query << " COUNT(id) AS count"
         elsif options[:fields]
diff --git a/lib/postal/message_db/delivery.rb b/lib/postal/message_db/delivery.rb
index f06c76b..0712122 100644
--- a/lib/postal/message_db/delivery.rb
+++ b/lib/postal/message_db/delivery.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class Delivery
diff --git a/lib/postal/message_db/live_stats.rb b/lib/postal/message_db/live_stats.rb
index 1ed9547..379af13 100644
--- a/lib/postal/message_db/live_stats.rb
+++ b/lib/postal/message_db/live_stats.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class LiveStats
diff --git a/lib/postal/message_db/load.rb b/lib/postal/message_db/load.rb
index a87df02..0a2a3a3 100644
--- a/lib/postal/message_db/load.rb
+++ b/lib/postal/message_db/load.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class Load
diff --git a/lib/postal/message_db/message.rb b/lib/postal/message_db/message.rb
index e54d77d..5b333ec 100644
--- a/lib/postal/message_db/message.rb
+++ b/lib/postal/message_db/message.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class Message
diff --git a/lib/postal/message_db/migration.rb b/lib/postal/message_db/migration.rb
index e209151..0acbabf 100644
--- a/lib/postal/message_db/migration.rb
+++ b/lib/postal/message_db/migration.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class Migration
diff --git a/lib/postal/message_db/migrations/01_create_migrations.rb b/lib/postal/message_db/migrations/01_create_migrations.rb
index af1358b..1fe2a6c 100644
--- a/lib/postal/message_db/migrations/01_create_migrations.rb
+++ b/lib/postal/message_db/migrations/01_create_migrations.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/02_create_messages.rb b/lib/postal/message_db/migrations/02_create_messages.rb
index 85d0086..ad476d1 100644
--- a/lib/postal/message_db/migrations/02_create_messages.rb
+++ b/lib/postal/message_db/migrations/02_create_messages.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/03_create_deliveries.rb b/lib/postal/message_db/migrations/03_create_deliveries.rb
index a1ff299..684877d 100644
--- a/lib/postal/message_db/migrations/03_create_deliveries.rb
+++ b/lib/postal/message_db/migrations/03_create_deliveries.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/04_create_live_stats.rb b/lib/postal/message_db/migrations/04_create_live_stats.rb
index 51824b8..acf19e9 100644
--- a/lib/postal/message_db/migrations/04_create_live_stats.rb
+++ b/lib/postal/message_db/migrations/04_create_live_stats.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/05_create_raw_message_sizes.rb b/lib/postal/message_db/migrations/05_create_raw_message_sizes.rb
index ecba2a0..c57ca0c 100644
--- a/lib/postal/message_db/migrations/05_create_raw_message_sizes.rb
+++ b/lib/postal/message_db/migrations/05_create_raw_message_sizes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/06_create_clicks.rb b/lib/postal/message_db/migrations/06_create_clicks.rb
index 19d8c66..bcb4b13 100644
--- a/lib/postal/message_db/migrations/06_create_clicks.rb
+++ b/lib/postal/message_db/migrations/06_create_clicks.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/07_create_loads.rb b/lib/postal/message_db/migrations/07_create_loads.rb
index 4ebfde3..3f6caa7 100644
--- a/lib/postal/message_db/migrations/07_create_loads.rb
+++ b/lib/postal/message_db/migrations/07_create_loads.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/08_create_stats.rb b/lib/postal/message_db/migrations/08_create_stats.rb
index b31955d..d583f66 100644
--- a/lib/postal/message_db/migrations/08_create_stats.rb
+++ b/lib/postal/message_db/migrations/08_create_stats.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/09_create_links.rb b/lib/postal/message_db/migrations/09_create_links.rb
index 96ddf4b..ade2629 100644
--- a/lib/postal/message_db/migrations/09_create_links.rb
+++ b/lib/postal/message_db/migrations/09_create_links.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/10_create_spam_checks.rb b/lib/postal/message_db/migrations/10_create_spam_checks.rb
index 4e5f272..64e2ca1 100644
--- a/lib/postal/message_db/migrations/10_create_spam_checks.rb
+++ b/lib/postal/message_db/migrations/10_create_spam_checks.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/11_add_time_to_deliveries.rb b/lib/postal/message_db/migrations/11_add_time_to_deliveries.rb
index f7fc4cc..f756928 100644
--- a/lib/postal/message_db/migrations/11_add_time_to_deliveries.rb
+++ b/lib/postal/message_db/migrations/11_add_time_to_deliveries.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/12_add_hold_expiry.rb b/lib/postal/message_db/migrations/12_add_hold_expiry.rb
index f7037ae..30dda0a 100644
--- a/lib/postal/message_db/migrations/12_add_hold_expiry.rb
+++ b/lib/postal/message_db/migrations/12_add_hold_expiry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/13_add_index_to_message_status.rb b/lib/postal/message_db/migrations/13_add_index_to_message_status.rb
index 94034bf..55673da 100644
--- a/lib/postal/message_db/migrations/13_add_index_to_message_status.rb
+++ b/lib/postal/message_db/migrations/13_add_index_to_message_status.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/14_create_suppressions.rb b/lib/postal/message_db/migrations/14_create_suppressions.rb
index 79c272e..cba6348 100644
--- a/lib/postal/message_db/migrations/14_create_suppressions.rb
+++ b/lib/postal/message_db/migrations/14_create_suppressions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/15_create_webhook_requests.rb b/lib/postal/message_db/migrations/15_create_webhook_requests.rb
index 90857aa..fec2402 100644
--- a/lib/postal/message_db/migrations/15_create_webhook_requests.rb
+++ b/lib/postal/message_db/migrations/15_create_webhook_requests.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/16_add_url_and_hook_to_webhooks.rb b/lib/postal/message_db/migrations/16_add_url_and_hook_to_webhooks.rb
index 49e9ef3..726712f 100644
--- a/lib/postal/message_db/migrations/16_add_url_and_hook_to_webhooks.rb
+++ b/lib/postal/message_db/migrations/16_add_url_and_hook_to_webhooks.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/17_add_replaced_link_count_to_messages.rb b/lib/postal/message_db/migrations/17_add_replaced_link_count_to_messages.rb
index df1075d..2616d01 100644
--- a/lib/postal/message_db/migrations/17_add_replaced_link_count_to_messages.rb
+++ b/lib/postal/message_db/migrations/17_add_replaced_link_count_to_messages.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/18_add_endpoints_to_messages.rb b/lib/postal/message_db/migrations/18_add_endpoints_to_messages.rb
index 9d872ce..551b58c 100644
--- a/lib/postal/message_db/migrations/18_add_endpoints_to_messages.rb
+++ b/lib/postal/message_db/migrations/18_add_endpoints_to_messages.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/19_convert_database_to_utf8mb4.rb b/lib/postal/message_db/migrations/19_convert_database_to_utf8mb4.rb
index b3d249c..192cf7e 100644
--- a/lib/postal/message_db/migrations/19_convert_database_to_utf8mb4.rb
+++ b/lib/postal/message_db/migrations/19_convert_database_to_utf8mb4.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/migrations/20_increase_links_url_size.rb b/lib/postal/message_db/migrations/20_increase_links_url_size.rb
index 3ed4f78..5fc406b 100644
--- a/lib/postal/message_db/migrations/20_increase_links_url_size.rb
+++ b/lib/postal/message_db/migrations/20_increase_links_url_size.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     module Migrations
diff --git a/lib/postal/message_db/provisioner.rb b/lib/postal/message_db/provisioner.rb
index b6ca1cf..70753c5 100644
--- a/lib/postal/message_db/provisioner.rb
+++ b/lib/postal/message_db/provisioner.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class Provisioner
diff --git a/lib/postal/message_db/statistics.rb b/lib/postal/message_db/statistics.rb
index 37976e0..5e410a1 100644
--- a/lib/postal/message_db/statistics.rb
+++ b/lib/postal/message_db/statistics.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class Statistics
diff --git a/lib/postal/message_db/suppression_list.rb b/lib/postal/message_db/suppression_list.rb
index fe683d5..4dc041f 100644
--- a/lib/postal/message_db/suppression_list.rb
+++ b/lib/postal/message_db/suppression_list.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class SuppressionList
diff --git a/lib/postal/message_db/webhooks.rb b/lib/postal/message_db/webhooks.rb
index 57855ee..6ccd25a 100644
--- a/lib/postal/message_db/webhooks.rb
+++ b/lib/postal/message_db/webhooks.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageDB
     class Webhooks
diff --git a/lib/postal/message_inspection.rb b/lib/postal/message_inspection.rb
index 402844e..67809d3 100644
--- a/lib/postal/message_inspection.rb
+++ b/lib/postal/message_inspection.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class MessageInspection
 
diff --git a/lib/postal/message_inspector.rb b/lib/postal/message_inspector.rb
index f522eb3..ad808d9 100644
--- a/lib/postal/message_inspector.rb
+++ b/lib/postal/message_inspector.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class MessageInspector
 
diff --git a/lib/postal/message_inspectors.rb b/lib/postal/message_inspectors.rb
index 7c083f1..200bb1b 100644
--- a/lib/postal/message_inspectors.rb
+++ b/lib/postal/message_inspectors.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageInspectors
   end
diff --git a/lib/postal/message_inspectors/clamav.rb b/lib/postal/message_inspectors/clamav.rb
index 0890601..28cab16 100644
--- a/lib/postal/message_inspectors/clamav.rb
+++ b/lib/postal/message_inspectors/clamav.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageInspectors
     class Clamav < MessageInspector
diff --git a/lib/postal/message_inspectors/rspamd.rb b/lib/postal/message_inspectors/rspamd.rb
index f52db16..506256a 100644
--- a/lib/postal/message_inspectors/rspamd.rb
+++ b/lib/postal/message_inspectors/rspamd.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "net/http"
 
 module Postal
diff --git a/lib/postal/message_inspectors/spam_assassin.rb b/lib/postal/message_inspectors/spam_assassin.rb
index 640d0dc..e2c4088 100644
--- a/lib/postal/message_inspectors/spam_assassin.rb
+++ b/lib/postal/message_inspectors/spam_assassin.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module MessageInspectors
     class SpamAssassin < MessageInspector
diff --git a/lib/postal/message_parser.rb b/lib/postal/message_parser.rb
index 956e19f..dd00c67 100644
--- a/lib/postal/message_parser.rb
+++ b/lib/postal/message_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class MessageParser
 
diff --git a/lib/postal/message_requeuer.rb b/lib/postal/message_requeuer.rb
index ec4d2e3..be8a788 100644
--- a/lib/postal/message_requeuer.rb
+++ b/lib/postal/message_requeuer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class MessageRequeuer
 
diff --git a/lib/postal/mx_lookup.rb b/lib/postal/mx_lookup.rb
index a859c04..9e899a0 100644
--- a/lib/postal/mx_lookup.rb
+++ b/lib/postal/mx_lookup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class MXLookup
 
diff --git a/lib/postal/query_string.rb b/lib/postal/query_string.rb
index 9546baa..41a22e7 100644
--- a/lib/postal/query_string.rb
+++ b/lib/postal/query_string.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class QueryString
 
diff --git a/lib/postal/rabbit_mq.rb b/lib/postal/rabbit_mq.rb
index 50ac3f9..cab0413 100644
--- a/lib/postal/rabbit_mq.rb
+++ b/lib/postal/rabbit_mq.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "postal/config"
 require "bunny"
 
diff --git a/lib/postal/received_header.rb b/lib/postal/received_header.rb
index 4afbaf2..29d0d38 100644
--- a/lib/postal/received_header.rb
+++ b/lib/postal/received_header.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class ReceivedHeader
 
diff --git a/lib/postal/reply_separator.rb b/lib/postal/reply_separator.rb
index b27362e..ae46e84 100644
--- a/lib/postal/reply_separator.rb
+++ b/lib/postal/reply_separator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class ReplySeparator
 
@@ -19,7 +20,7 @@ module Postal
       return "" unless text.is_a?(String)
 
       text = text.gsub("\r", "")
-      stripped = ""
+      stripped = String.new
       RULES.each do |rule|
         text.gsub!(rule) do
           stripped = ::Regexp.last_match(0).to_s + "\n" + stripped
diff --git a/lib/postal/rspec_helpers.rb b/lib/postal/rspec_helpers.rb
index ddc875c..353091e 100644
--- a/lib/postal/rspec_helpers.rb
+++ b/lib/postal/rspec_helpers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module RspecHelpers
 
diff --git a/lib/postal/send_result.rb b/lib/postal/send_result.rb
index 251e075..9142db7 100644
--- a/lib/postal/send_result.rb
+++ b/lib/postal/send_result.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class SendResult
 
diff --git a/lib/postal/sender.rb b/lib/postal/sender.rb
index 7c4914a..b1b2cb6 100644
--- a/lib/postal/sender.rb
+++ b/lib/postal/sender.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class Sender
 
diff --git a/lib/postal/smtp_sender.rb b/lib/postal/smtp_sender.rb
index bd6121d..f5a65f9 100644
--- a/lib/postal/smtp_sender.rb
+++ b/lib/postal/smtp_sender.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "resolv"
 
 module Postal
diff --git a/lib/postal/smtp_server.rb b/lib/postal/smtp_server.rb
index ff56918..e35dcee 100644
--- a/lib/postal/smtp_server.rb
+++ b/lib/postal/smtp_server.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   module SMTPServer
   end
diff --git a/lib/postal/smtp_server/client.rb b/lib/postal/smtp_server/client.rb
index 7d93eb6..9e2df8f 100644
--- a/lib/postal/smtp_server/client.rb
+++ b/lib/postal/smtp_server/client.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "resolv"
 require "nifty/utils/random_string"
 
@@ -360,7 +361,7 @@ module Postal
           return "503 HELO/EHLO, MAIL FROM and RCPT TO before sending data"
         end
 
-        @data = "".force_encoding("BINARY")
+        @data = String.new.force_encoding("BINARY")
         @headers = {}
         @receiving_headers = true
 
diff --git a/lib/postal/smtp_server/server.rb b/lib/postal/smtp_server/server.rb
index 5aae3fb..30ca632 100644
--- a/lib/postal/smtp_server/server.rb
+++ b/lib/postal/smtp_server/server.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "ipaddr"
 require "nio"
 
diff --git a/lib/postal/spam_check.rb b/lib/postal/spam_check.rb
index b0ab968..3c0270d 100644
--- a/lib/postal/spam_check.rb
+++ b/lib/postal/spam_check.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class SpamCheck
 
diff --git a/lib/postal/tracking_middleware.rb b/lib/postal/tracking_middleware.rb
index 3386b58..bba9ee7 100644
--- a/lib/postal/tracking_middleware.rb
+++ b/lib/postal/tracking_middleware.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class TrackingMiddleware
 
diff --git a/lib/postal/user_creator.rb b/lib/postal/user_creator.rb
index a8b32d0..57dd8f1 100644
--- a/lib/postal/user_creator.rb
+++ b/lib/postal/user_creator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "highline"
 
 module Postal
diff --git a/lib/postal/version.rb b/lib/postal/version.rb
index 80d20d0..0991253 100644
--- a/lib/postal/version.rb
+++ b/lib/postal/version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
 
   VERSION_PATH = File.expand_path("../../VERSION", __dir__)
diff --git a/lib/postal/worker.rb b/lib/postal/worker.rb
index e738841..f00d7c0 100644
--- a/lib/postal/worker.rb
+++ b/lib/postal/worker.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Postal
   class Worker
 
diff --git a/lib/tasks/auto_annotate_models.rake b/lib/tasks/auto_annotate_models.rake
index 1920150..069c1a5 100644
--- a/lib/tasks/auto_annotate_models.rake
+++ b/lib/tasks/auto_annotate_models.rake
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # NOTE: only doing this in development as some production environments (Heroku)
 # NOTE: are sensitive to local FS writes, and besides -- it's just not proper
 # NOTE: to have a dev-mode tool do its thing in production.
diff --git a/lib/tasks/postal.rake b/lib/tasks/postal.rake
index 480f9f4..fb8cdda 100644
--- a/lib/tasks/postal.rake
+++ b/lib/tasks/postal.rake
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 namespace :postal do
   desc "Start the cron worker"
   task cron: :environment do
diff --git a/script/default_dkim_record.rb b/script/default_dkim_record.rb
index 50c8a30..5f25d04 100644
--- a/script/default_dkim_record.rb
+++ b/script/default_dkim_record.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 require File.expand_path("../lib/postal/config", __dir__)
 puts Postal.rp_dkim_dns_record
diff --git a/script/generate_initial_config.rb b/script/generate_initial_config.rb
index 131b4cb..6763541 100755
--- a/script/generate_initial_config.rb
+++ b/script/generate_initial_config.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 require File.expand_path("../lib/postal/config", __dir__)
 require "openssl"
 require "securerandom"
diff --git a/script/insert-bounce.rb b/script/insert-bounce.rb
index 81d4c2e..dfcf88b 100755
--- a/script/insert-bounce.rb
+++ b/script/insert-bounce.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 
 # This script will insert a message into your database that looks like a bounce
 # for a message that you specify.
diff --git a/script/make_user.rb b/script/make_user.rb
index 79db624..11a4067 100755
--- a/script/make_user.rb
+++ b/script/make_user.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 trap("INT") do
   puts
   exit
diff --git a/script/queue_size.rb b/script/queue_size.rb
index d14a966..a39b616 100755
--- a/script/queue_size.rb
+++ b/script/queue_size.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 require_relative "../lib/postal/config"
 require "mysql2"
 
diff --git a/script/test_app_smtp.rb b/script/test_app_smtp.rb
index a7b009d..cacc6d6 100755
--- a/script/test_app_smtp.rb
+++ b/script/test_app_smtp.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 trap("INT") do
   puts
   exit
diff --git a/script/version.rb b/script/version.rb
index 0bd3a3c..f58848e 100755
--- a/script/version.rb
+++ b/script/version.rb
@@ -1,3 +1,4 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 require File.expand_path("../lib/postal/version", __dir__)
 puts Postal.version
diff --git a/script/worker.rb b/script/worker.rb
index 3642577..834de2a 100755
--- a/script/worker.rb
+++ b/script/worker.rb
@@ -1,3 +1,4 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 require_relative "../config/environment"
 Postal::Worker.new([:main]).work
diff --git a/spec/app/models/organization_spec.rb b/spec/app/models/organization_spec.rb
index bde3f5e..61b7f39 100644
--- a/spec/app/models/organization_spec.rb
+++ b/spec/app/models/organization_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rails_helper"
 
 describe Organization do
diff --git a/spec/app/models/outgoing_message_prototype_spec.rb b/spec/app/models/outgoing_message_prototype_spec.rb
index ff71716..e40f336 100644
--- a/spec/app/models/outgoing_message_prototype_spec.rb
+++ b/spec/app/models/outgoing_message_prototype_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rails_helper"
 
 describe OutgoingMessagePrototype do
diff --git a/spec/app/models/server_spec.rb b/spec/app/models/server_spec.rb
index 049dfff..6b56a11 100644
--- a/spec/app/models/server_spec.rb
+++ b/spec/app/models/server_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rails_helper"
 
 describe Server do
diff --git a/spec/app/models/user_spec.rb b/spec/app/models/user_spec.rb
index f955561..d4137fd 100644
--- a/spec/app/models/user_spec.rb
+++ b/spec/app/models/user_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rails_helper"
 
 describe User do
diff --git a/spec/factories/domain_factory.rb b/spec/factories/domain_factory.rb
index 0a61d55..8a20907 100644
--- a/spec/factories/domain_factory.rb
+++ b/spec/factories/domain_factory.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: domains
diff --git a/spec/factories/organization_factory.rb b/spec/factories/organization_factory.rb
index 843c0f4..8f49098 100644
--- a/spec/factories/organization_factory.rb
+++ b/spec/factories/organization_factory.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: organizations
diff --git a/spec/factories/server_factory.rb b/spec/factories/server_factory.rb
index 3397cd2..6143310 100644
--- a/spec/factories/server_factory.rb
+++ b/spec/factories/server_factory.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: servers
diff --git a/spec/factories/track_domain_factory.rb b/spec/factories/track_domain_factory.rb
index 64a7d62..4d2aafd 100644
--- a/spec/factories/track_domain_factory.rb
+++ b/spec/factories/track_domain_factory.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: track_domains
diff --git a/spec/factories/user_factory.rb b/spec/factories/user_factory.rb
index a4a0f02..b266092 100644
--- a/spec/factories/user_factory.rb
+++ b/spec/factories/user_factory.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # == Schema Information
 #
 # Table name: users
diff --git a/spec/lib/postal/message_db/connection_pool_spec.rb b/spec/lib/postal/message_db/connection_pool_spec.rb
index 73760e0..a8cd9d2 100644
--- a/spec/lib/postal/message_db/connection_pool_spec.rb
+++ b/spec/lib/postal/message_db/connection_pool_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rails_helper"
 
 describe Postal::MessageDB::ConnectionPool do
diff --git a/spec/lib/postal/message_db/database_spec.rb b/spec/lib/postal/message_db/database_spec.rb
index 00995e1..66f22a1 100644
--- a/spec/lib/postal/message_db/database_spec.rb
+++ b/spec/lib/postal/message_db/database_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rails_helper"
 
 describe Postal::MessageDB::Database do
diff --git a/spec/lib/postal/message_parser_spec.rb b/spec/lib/postal/message_parser_spec.rb
index c47a229..f27de67 100644
--- a/spec/lib/postal/message_parser_spec.rb
+++ b/spec/lib/postal/message_parser_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rails_helper"
 
 describe Postal::MessageParser do
diff --git a/spec/lib/postal/query_string_spec.rb b/spec/lib/postal/query_string_spec.rb
index 1e34488..2778cac 100644
--- a/spec/lib/postal/query_string_spec.rb
+++ b/spec/lib/postal/query_string_spec.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rails_helper"
 
 describe Postal::QueryString do
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index b4de236..76fbfc1 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 ENV["POSTAL_ENV"] = "test"
 
 require File.expand_path("../config/environment", __dir__)
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index a4e3954..fd7237d 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 RSpec.configure do |config|
   config.color = true