diff --git a/Gemfile b/Gemfile
index 9772788..8c9fe26 100644
--- a/Gemfile
+++ b/Gemfile
@@ -52,6 +52,7 @@ group :development do
   gem "rspec-rails", require: false
   gem "rubocop"
   gem "rubocop-rails"
+  gem "shoulda-matchers"
   gem "timecop"
   gem "webmock"
 end
diff --git a/Gemfile.lock b/Gemfile.lock
index 2471753..476e924 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -289,6 +289,8 @@ GEM
       sentry-ruby (~> 5.8.0)
     sentry-ruby (5.8.0)
       concurrent-ruby (~> 1.0, >= 1.0.2)
+    shoulda-matchers (6.1.0)
+      activesupport (>= 5.2.0)
     sprockets (4.2.0)
       concurrent-ruby (~> 1.0)
       rack (>= 2.2.4, < 4)
@@ -366,6 +368,7 @@ DEPENDENCIES
   secure_headers
   sentry-rails
   sentry-ruby
+  shoulda-matchers
   timecop
   turbolinks (~> 5)
   uglifier (>= 1.3.0)
diff --git a/app/models/server.rb b/app/models/server.rb
index 942f40c..43cfe35 100644
--- a/app/models/server.rb
+++ b/app/models/server.rb
@@ -192,15 +192,22 @@ class Server < ApplicationRecord
   end
 
   def send_limit_approaching?
-    send_limit && (send_volume >= send_limit * 0.90)
+    return false unless send_limit
+
+    (send_volume >= send_limit * 0.90)
   end
 
   def send_limit_exceeded?
-    send_limit && send_volume >= send_limit
+    return false unless send_limit
+
+    send_volume >= send_limit
   end
 
   def send_limit_warning(type)
-    AppMailer.send("server_send_limit_#{type}", self).deliver
+    if organization.notification_addresses.present?
+      AppMailer.send("server_send_limit_#{type}", self).deliver
+    end
+
     update_column("send_limit_#{type}_notified_at", Time.now)
     WebhookRequest.trigger(self, "SendLimit#{type.to_s.capitalize}", server: webhook_hash, volume: send_volume, limit: send_limit)
   end
@@ -209,17 +216,6 @@ class Server < ApplicationRecord
     @queue_size ||= queued_messages.ready.count
   end
 
-  def stats
-    {
-      queue: queue_size,
-      held: held_messages,
-      bounce_rate: bounce_rate,
-      message_rate: message_rate,
-      throughput: throughput_stats,
-      size: message_db.total_size
-    }
-  end
-
   # Return the domain which can be used to authenticate emails sent from the given e-mail address.
   #
   # @param address [String] an e-mail address
@@ -274,7 +270,10 @@ class Server < ApplicationRecord
     self.suspended_at = Time.now
     self.suspension_reason = reason
     save!
-    AppMailer.server_suspended(self).deliver
+    if organization.notification_addresses.present?
+      AppMailer.server_suspended(self).deliver
+    end
+    true
   end
 
   def unsuspend
@@ -283,12 +282,6 @@ class Server < ApplicationRecord
     save!
   end
 
-  def validate_ip_pool_belongs_to_organization
-    return unless ip_pool && ip_pool_id_changed? && !organization.ip_pools.include?(ip_pool)
-
-    errors.add :ip_pool_id, "must belong to the organization"
-  end
-
   def ip_pool_for_message(message)
     return unless message.scope == "outgoing"
 
@@ -300,46 +293,48 @@ class Server < ApplicationRecord
         end
       end
     end
+
     ip_pool
   end
 
-  def self.triggered_send_limit(type)
-    servers = where("send_limit_#{type}_at IS NOT NULL AND send_limit_#{type}_at > ?", 3.minutes.ago)
-    servers.where("send_limit_#{type}_notified_at IS NULL OR send_limit_#{type}_notified_at < ?", 1.hour.ago)
+  private
+
+  def validate_ip_pool_belongs_to_organization
+    return unless ip_pool && ip_pool_id_changed? && !organization.ip_pools.include?(ip_pool)
+
+    errors.add :ip_pool_id, "must belong to the organization"
   end
 
-  def self.send_send_limit_notifications
-    [:approaching, :exceeded].each_with_object({}) do |type, hash|
-      hash[type] = 0
-      servers = triggered_send_limit(type)
-      next if servers.empty?
+  class << self
 
-      servers.each do |server|
-        hash[type] += 1
-        server.send_limit_warning(type)
-      end
-    end
-  end
-
-  def self.[](id, extra = nil)
-    server = nil
-    if id.is_a?(String)
-      if id =~ /\A(\w+)\/(\w+)\z/
-        server = includes(:organization).where(organizations: { permalink: ::Regexp.last_match(1) }, permalink: ::Regexp.last_match(2)).first
-      end
-    else
-      server = where(id: id).first
+    def triggered_send_limit(type)
+      servers = where("send_limit_#{type}_at IS NOT NULL AND send_limit_#{type}_at > ?", 3.minutes.ago)
+      servers.where("send_limit_#{type}_notified_at IS NULL OR send_limit_#{type}_notified_at < ?", 1.hour.ago)
     end
 
-    if extra
-      if extra.is_a?(String)
-        server.domains.where(name: extra.to_s).first
+    def send_send_limit_notifications
+      [:approaching, :exceeded].each_with_object({}) do |type, hash|
+        hash[type] = 0
+        servers = triggered_send_limit(type)
+        next if servers.empty?
+
+        servers.each do |server|
+          hash[type] += 1
+          server.send_limit_warning(type)
+        end
+      end
+    end
+
+    def [](id, extra = nil)
+      if id.is_a?(String) && id =~ /\A(\w+)\/(\w+)\z/
+        joins(:organization).where(
+          organizations: { permalink: ::Regexp.last_match(1) }, permalink: ::Regexp.last_match(2)
+        ).first
       else
-        server.message(extra.to_i)
+        find_by(id: id.to_i)
       end
-    else
-      server
     end
+
   end
 
 end
diff --git a/config/initializers/smtp.rb b/config/initializers/smtp.rb
index dcc06a1..fc5c7c1 100644
--- a/config/initializers/smtp.rb
+++ b/config/initializers/smtp.rb
@@ -3,6 +3,8 @@
 require "postal/config"
 
 if Postal.config&.smtp
+  # TODO: by default, we should just send mail through the local Postal
+  # installation rather than having to actually configure an SMTP server.
   ActionMailer::Base.delivery_method = :smtp
   ActionMailer::Base.smtp_settings = { address: Postal.config.smtp.host, user_name: Postal.config.smtp.username, password: Postal.config.smtp.password, port: Postal.config.smtp.port || 25 }
 end
diff --git a/spec/app/models/server_spec.rb b/spec/app/models/server_spec.rb
deleted file mode 100644
index f871408..0000000
--- a/spec/app/models/server_spec.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-# frozen_string_literal: true
-
-require "rails_helper"
-
-describe Server do
-  context "model" do
-    subject(:server) { create(:server) }
-
-    it "should have a UUID" do
-      expect(server.uuid).to be_a String
-      expect(server.uuid.length).to eq 36
-    end
-  end
-end
diff --git a/spec/factories/domain_factory.rb b/spec/factories/domain_factory.rb
index fe9ca66..4aeebe8 100644
--- a/spec/factories/domain_factory.rb
+++ b/spec/factories/domain_factory.rb
@@ -42,6 +42,17 @@ FactoryBot.define do
     sequence(:name) { |n| "example#{n}.com" }
     verification_method { "DNS" }
     verified_at { Time.now }
+
+    trait :unverified do
+      verified_at { nil }
+    end
+
+    trait :dns_all_ok do
+      spf_status { "OK" }
+      dkim_status { "OK" }
+      mx_status { "OK" }
+      return_path_status { "OK" }
+    end
   end
 
   factory :organization_domain, parent: :domain do
diff --git a/spec/factories/ip_pool_rule_factory.rb b/spec/factories/ip_pool_rule_factory.rb
new file mode 100644
index 0000000..0a75af2
--- /dev/null
+++ b/spec/factories/ip_pool_rule_factory.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :ip_pool_rule do
+    owner factory: :organization
+    ip_pool
+    to_text { "google.com" }
+
+    after(:build) do |ip_pool_rule|
+      if ip_pool_rule.ip_pool.organizations.empty? && ip_pool_rule.owner.is_a?(Organization)
+        ip_pool_rule.ip_pool.organizations << ip_pool_rule.owner
+      end
+    end
+  end
+end
diff --git a/spec/factories/organization_factory.rb b/spec/factories/organization_factory.rb
index 937a33d..e35812e 100644
--- a/spec/factories/organization_factory.rb
+++ b/spec/factories/organization_factory.rb
@@ -28,5 +28,10 @@ FactoryBot.define do
     name { "Acme Inc" }
     sequence(:permalink) { |n| "org#{n}" }
     association :owner, factory: :user
+
+    trait :suspended do
+      suspended_at { 1.day.ago }
+      suspension_reason { "test" }
+    end
   end
 end
diff --git a/spec/factories/server_factory.rb b/spec/factories/server_factory.rb
index 6b9b60d..ac19936 100644
--- a/spec/factories/server_factory.rb
+++ b/spec/factories/server_factory.rb
@@ -52,6 +52,7 @@ FactoryBot.define do
 
     trait :suspended do
       suspended_at { Time.current }
+      suspension_reason { "Test Reason" }
     end
 
     trait :exceeded_send_limit do
diff --git a/spec/app/models/organization_spec.rb b/spec/models/organization_spec.rb
similarity index 100%
rename from spec/app/models/organization_spec.rb
rename to spec/models/organization_spec.rb
diff --git a/spec/app/models/outgoing_message_prototype_spec.rb b/spec/models/outgoing_message_prototype_spec.rb
similarity index 100%
rename from spec/app/models/outgoing_message_prototype_spec.rb
rename to spec/models/outgoing_message_prototype_spec.rb
diff --git a/spec/models/server_spec.rb b/spec/models/server_spec.rb
new file mode 100644
index 0000000..e7b78d3
--- /dev/null
+++ b/spec/models/server_spec.rb
@@ -0,0 +1,614 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe Server do
+  subject(:server) { build(:server) }
+
+  describe "relationships" do
+    it { is_expected.to belong_to(:organization) }
+    it { is_expected.to belong_to(:ip_pool).optional }
+    it { is_expected.to have_many(:domains) }
+    it { is_expected.to have_many(:credentials) }
+    it { is_expected.to have_many(:smtp_endpoints) }
+    it { is_expected.to have_many(:http_endpoints) }
+    it { is_expected.to have_many(:address_endpoints) }
+    it { is_expected.to have_many(:routes) }
+    it { is_expected.to have_many(:queued_messages) }
+    it { is_expected.to have_many(:webhooks) }
+    it { is_expected.to have_many(:webhook_requests) }
+    it { is_expected.to have_many(:track_domains) }
+    it { is_expected.to have_many(:ip_pool_rules) }
+  end
+
+  describe "validations" do
+    it { is_expected.to validate_presence_of(:name) }
+    it { is_expected.to validate_uniqueness_of(:name).scoped_to(:organization_id).case_insensitive }
+    it { is_expected.to validate_inclusion_of(:mode).in_array(Server::MODES) }
+    it { is_expected.to validate_uniqueness_of(:permalink).scoped_to(:organization_id).case_insensitive }
+    it { is_expected.to validate_exclusion_of(:permalink).in_array(Server::RESERVED_PERMALINKS) }
+    it { is_expected.to allow_value("hello").for(:permalink) }
+    it { is_expected.to allow_value("hello-world").for(:permalink) }
+    it { is_expected.to allow_value("hello1234").for(:permalink) }
+    it { is_expected.not_to allow_value("LARGE").for(:permalink) }
+    it { is_expected.not_to allow_value(" lots of spaces ").for(:permalink) }
+    it { is_expected.not_to allow_value("hello+").for(:permalink) }
+    it { is_expected.not_to allow_value("!!!").for(:permalink) }
+    it { is_expected.not_to allow_value("[hello]").for(:permalink) }
+
+    describe "ip pool validation" do
+      let(:org) { create(:organization) }
+      let(:ip_pool) { create(:ip_pool) }
+      let(:server) { build(:server, organization: org, ip_pool: ip_pool) }
+
+      context "when the IP pool does not belong to the same organization" do
+        it "adds an error" do
+          expect(server.save).to be false
+          expect(server.errors[:ip_pool_id]).to include(/must belong to the organization/)
+        end
+      end
+
+      context "whent he IP pool does belong to the the same organization" do
+        before do
+          org.ip_pools << ip_pool
+        end
+
+        it "does not add an error" do
+          expect(server.save).to be true
+        end
+      end
+    end
+  end
+
+  describe "creation" do
+    let(:server) { build(:server) }
+
+    it "generates a uuid" do
+      expect { server.save }.to change { server.uuid }.from(nil).to(/[a-f0-9-]{36}/)
+    end
+
+    it "generates a token" do
+      expect { server.save }.to change { server.token }.from(nil).to(/[a-z0-9]{6}/)
+    end
+
+    it "provisions a database" do
+      expect(server.message_db.provisioner).to receive(:provision).once
+      server.provision_database = true
+      server.save
+    end
+  end
+
+  describe "deletion" do
+    it "removes the database" do
+      expect(server.message_db.provisioner).to receive(:drop).once
+      server.provision_database = true
+      server.destroy
+    end
+  end
+
+  describe "#status" do
+    context "when the server is suspended" do
+      let(:server) { build(:server, :suspended) }
+
+      it "returns Suspended" do
+        expect(server.status).to eq("Suspended")
+      end
+    end
+
+    context "when the server is not suspended" do
+      it "returns the mode" do
+        expect(server.status).to eq "Live"
+      end
+    end
+  end
+
+  describe "#full_permalink" do
+    it "returns the org and server permalinks concatenated" do
+      expect(server.full_permalink).to eq "#{server.organization.permalink}/#{server.permalink}"
+    end
+  end
+
+  describe "#suspended?" do
+    context "when the server is suspended" do
+      let(:server) { build(:server, :suspended) }
+
+      it "returns true" do
+        expect(server).to be_suspended
+      end
+    end
+
+    context "when the server is not suspended" do
+      it "returns false" do
+        expect(server).not_to be_suspended
+      end
+    end
+  end
+
+  describe "#actual_suspension_reason" do
+    context "when the server is not suspended" do
+      it "returns nil" do
+        expect(server.actual_suspension_reason).to be_nil
+      end
+    end
+
+    context "when the server is not suspended by the organization is" do
+      let(:org) { build(:organization, :suspended, suspension_reason: "org test") }
+      let(:server) { build(:server, organization: org) }
+
+      it "returns the organization suspension reason" do
+        expect(server.actual_suspension_reason).to eq "org test"
+      end
+    end
+
+    context "when the server is suspended" do
+      let(:server) { build(:server, :suspended, suspension_reason: "server test") }
+
+      it "returns the suspension reason" do
+        expect(server.actual_suspension_reason).to eq "server test"
+      end
+    end
+  end
+
+  describe "#to_param" do
+    it "returns the permalink" do
+      expect(server.to_param).to eq server.permalink
+    end
+  end
+
+  describe "#message_db" do
+    it "returns a message DB instance" do
+      expect(server.message_db).to be_a Postal::MessageDB::Database
+      expect(server.message_db).to have_attributes(server_id: server.id, organization_id: server.organization.id)
+    end
+
+    it "caches the value" do
+      call1 = server.message_db
+      call2 = server.message_db
+      expect(call1.object_id).to eq(call2.object_id)
+    end
+  end
+
+  describe "#message" do
+    it "delegates to the message db" do
+      expect(server.message_db).to receive(:message).with(1)
+      server.message(1)
+    end
+  end
+
+  describe "#message_rate" do
+    it "returns the live stats for the last hour per minute" do
+      allow(server.message_db.live_stats).to receive(:total).and_return(600)
+      expect(server.message_rate).to eq 10
+      expect(server.message_db.live_stats).to have_received(:total).with(60, types: [:incoming, :outgoing])
+    end
+  end
+
+  describe "#held_messages" do
+    it "returns the number of held messages" do
+      expect(server.message_db).to receive(:messages).with(count: true, where: { held: true }).and_return(50)
+      expect(server.held_messages).to eq 50
+    end
+  end
+
+  describe "#throughput_stats" do
+    before do
+      allow(server.message_db.live_stats).to receive(:total).with(60, types: [:incoming]).and_return(50)
+      allow(server.message_db.live_stats).to receive(:total).with(60, types: [:outgoing]).and_return(100)
+    end
+
+    context "when the server has a sent limit" do
+      let(:server) { build(:server, send_limit: 500) }
+
+      it "returns the stats with an outgoing usage percentage" do
+        expect(server.throughput_stats).to eq({
+          incoming: 50,
+          outgoing: 100,
+          outgoing_usage: 20.0
+        })
+      end
+    end
+
+    context "when the server does not have a sent limit" do
+      it "returns the stats with no outgoing usage percentage" do
+        expect(server.throughput_stats).to eq({
+          incoming: 50,
+          outgoing: 100,
+          outgoing_usage: 0
+        })
+      end
+    end
+  end
+
+  describe "#bounce_rate" do
+    context "when there are no outgoing emails" do
+      it "returns zero" do
+        expect(server.bounce_rate).to eq 0
+      end
+    end
+
+    context "when there are outgoing emails with some bounces" do
+      it "returns the rate" do
+        allow(server.message_db.statistics).to receive(:get).with(:daily, [:outgoing, :bounces], kind_of(Time), 30)
+                                                            .and_return({
+                                                                          10.minutes.ago => { outgoing: 150, bounces: 50 },
+                                                                          5.minutes.ago => { outgoing: 350, bounces: 30 },
+                                                                          1.minutes.ago => { outgoing: 500, bounces: 20 }
+                                                                        })
+        expect(server.bounce_rate).to eq 10.0
+      end
+    end
+  end
+
+  describe "#domain_stats" do
+    it "returns stats about the domains associated with the server" do
+      create(:domain, owner: server) # verified, bad dns
+      create(:domain, :unverified, owner: server) # unverified
+      create(:domain, :dns_all_ok, owner: server) # verified good dns
+
+      expect(server.domain_stats).to eq [3, 1, 1]
+    end
+  end
+
+  describe "#webhook_hash" do
+    it "returns a hash to represent the server" do
+      expect(server.webhook_hash).to eq({
+        uuid: server.uuid,
+        name: server.name,
+        permalink: server.permalink,
+        organization: server.organization.permalink
+      })
+    end
+  end
+
+  describe "#send_volume" do
+    it "returns the number of outgoing messages sent in the last hour" do
+      allow(server.message_db.live_stats).to receive(:total).with(60, types: [:outgoing]).and_return(50)
+      expect(server.send_volume).to eq 50
+    end
+  end
+
+  describe "#send_limit_approaching?" do
+    context "when the server has no send limit" do
+      it "returns false" do
+        expect(server.send_limit_approaching?).to be false
+      end
+    end
+
+    context "when the server has a send limit" do
+      let(:server) { build(:server, send_limit: 1000) }
+
+      context "when the server's send volume is less 90% of the limit" do
+        it "return false" do
+          allow(server).to receive(:send_volume).and_return(800)
+          expect(server.send_limit_approaching?).to be false
+        end
+      end
+
+      context "when the server's send volume is more than 90% of the limit" do
+        it "returns true" do
+          allow(server).to receive(:send_volume).and_return(901)
+          expect(server.send_limit_approaching?).to be true
+        end
+      end
+    end
+  end
+
+  describe "#send_limit_warning" do
+    let(:server) { create(:server, send_limit: 1000) }
+
+    before do
+      allow(server).to receive(:send_volume).and_return(500)
+    end
+
+    context "when given the :approaching argument" do
+      it "sends an email to the org notification addresses" do
+        server.organization.users << create(:user)
+
+        server.send_limit_warning(:approaching)
+        delivery = ActionMailer::Base.deliveries.last
+        expect(delivery).to have_attributes(subject: /mail server is approaching its send limit/i)
+      end
+
+      it "sets the notification time" do
+        expect { server.send_limit_warning(:approaching) }.to change { server.send_limit_approaching_notified_at }
+          .from(nil).to(kind_of(Time))
+      end
+
+      it "triggers a webhook" do
+        expect(WebhookRequest).to receive(:trigger).with(server, "SendLimitApproaching", server: server.webhook_hash, volume: 500, limit: 1000)
+        server.send_limit_warning(:approaching)
+      end
+    end
+
+    context "when given the :exceeded argument" do
+      it "sends an email to the org notification addresses" do
+        server.organization.users << create(:user)
+
+        server.send_limit_warning(:exceeded)
+        delivery = ActionMailer::Base.deliveries.last
+        expect(delivery).to have_attributes(subject: /mail server has exceeded its send limit/i)
+      end
+
+      it "sets the notification time" do
+        expect { server.send_limit_warning(:exceeded) }.to change { server.send_limit_exceeded_notified_at }
+          .from(nil).to(kind_of(Time))
+      end
+
+      it "triggers a webhook" do
+        expect(WebhookRequest).to receive(:trigger).with(server, "SendLimitExceeded", server: server.webhook_hash, volume: 500, limit: 1000)
+        server.send_limit_warning(:exceeded)
+      end
+    end
+  end
+
+  describe "#queue_size" do
+    it "returns the number of queued messages that are ready" do
+      create(:queued_message, server: server, retry_after: nil)
+      create(:queued_message, server: server, retry_after: 1.minute.ago)
+      expect(server.queue_size).to eq 2
+    end
+  end
+
+  describe "#authenticated_domain_for_address" do
+    context "when the address given is blank" do
+      it "returns nil" do
+        expect(server.authenticated_domain_for_address("")).to be nil
+        expect(server.authenticated_domain_for_address(nil)).to be nil
+      end
+    end
+
+    context "when the address given does not have a username & domain component" do
+      it "returns nil" do
+        expect(server.authenticated_domain_for_address("blah")).to be nil
+      end
+    end
+
+    context "when there is a verified org-level domain matching the address provided" do
+      it "returns that domain" do
+        server = create(:server)
+        domain = create(:domain, owner: server.organization, name: "mangos.io")
+        expect(server.authenticated_domain_for_address("hello@mangos.io")).to eq domain
+      end
+    end
+
+    context "when there is a verified server-level domain matching the address provided" do
+      it "returns that domain" do
+        domain = create(:domain, owner: server, name: "oranges.io")
+        expect(server.authenticated_domain_for_address("hello@oranges.io")).to eq domain
+      end
+    end
+
+    context "when there is a verified server-level domain matching the address and a use_for_any" do
+      it "returns the matching domain" do
+        domain = create(:domain, owner: server, name: "oranges.io")
+        create(:domain, owner: server, name: "pears.com", use_for_any: true)
+        expect(server.authenticated_domain_for_address("hello@oranges.io")).to eq domain
+      end
+    end
+
+    context "when there is a verified server-level and org-level domain with the same name" do
+      it "returns the server-level domain" do
+        domain = create(:domain, owner: server, name: "lemons.com")
+        create(:domain, owner: server.organization, name: "lemons.com")
+        expect(server.authenticated_domain_for_address("hello@lemons.com")).to eq domain
+      end
+    end
+
+    context "when there is a verified server-level domain with the 'use_for_any' boolean set with a different name" do
+      it "returns that domain" do
+        create(:domain, owner: server, name: "pears.com")
+        domain = create(:domain, owner: server, name: "apples.io", use_for_any: true)
+        expect(server.authenticated_domain_for_address("hello@bananas.com")).to eq domain
+      end
+    end
+
+    context "when there is no suitable domain" do
+      it "returns nil" do
+        server = create(:server)
+        create(:domain, owner: server, name: "pears.com")
+        create(:domain, owner: server.organization, name: "pineapples.com")
+        expect(server.authenticated_domain_for_address("hello@bananas.com")).to be nil
+      end
+    end
+  end
+
+  describe "#find_authenticated_domain_from_headers" do
+    context "when none of the from addresses have a valid domain" do
+      it "returns nil" do
+        expect(server.find_authenticated_domain_from_headers("from" => "test@lemons.com")).to be nil
+      end
+    end
+
+    context "when the from addresses has a valid domain" do
+      it "returns the domain" do
+        domain = create(:domain, owner: server)
+        expect(server.find_authenticated_domain_from_headers("from" => "hello@#{domain.name}")).to eq domain
+      end
+    end
+
+    context "when there are multiple from addresses" do
+      context "when none of them match a domain" do
+        it "returns nil" do
+          expect(server.find_authenticated_domain_from_headers("from" => ["hello@lemons.com", "hello@apples.com"])).to be nil
+        end
+      end
+
+      context "when some but not all match" do
+        it "returns nil" do
+          domain = create(:domain, owner: server)
+          expect(server.find_authenticated_domain_from_headers("from" => ["hello@#{domain.name}", "hello@lemons.com"])).to be nil
+        end
+      end
+
+      context "when all match" do
+        it "returns the first domain that matched" do
+          domain1 = create(:domain, owner: server)
+          domain2 = create(:domain, owner: server)
+          expect(server.find_authenticated_domain_from_headers("from" => ["hello@#{domain1.name}", "hello@#{domain2.name}"])).to eq domain1
+        end
+      end
+    end
+
+    context "when the server is not allowed to use the sender header" do
+      context "when the sender header has a valid address" do
+        it "does not return the domain" do
+          domain = create(:domain, owner: server)
+          result = server.find_authenticated_domain_from_headers(
+            "from" => "hello@lemons.com",
+            "sender" => "hello@#{domain.name}"
+          )
+          expect(result).to be nil
+        end
+      end
+    end
+
+    context "when the server is allowed to use the sender header" do
+      let(:server) { build(:server, allow_sender: true) }
+
+      context "when none of the from addresses match but sender domains do" do
+        it "returns the domain that does match" do
+          domain = create(:domain, owner: server)
+          result = server.find_authenticated_domain_from_headers(
+            "from" => "hello@lemons.com",
+            "sender" => "hello@#{domain.name}"
+          )
+          expect(result).to eq domain
+        end
+      end
+    end
+  end
+
+  describe "#suspend" do
+    let(:server) { create(:server) }
+
+    it "sets the suspension time" do
+      expect { server.suspend("some reason") }.to change { server.reload.suspended_at }.from(nil).to(kind_of(Time))
+    end
+
+    it "sets the suspension reason" do
+      expect { server.suspend("some reason") }.to change { server.reload.suspension_reason }.from(nil).to("some reason")
+    end
+
+    context "when there are no notification addresses" do
+      it "does not send an email" do
+        server.suspend("some reason")
+        expect(ActionMailer::Base.deliveries).to be_empty
+      end
+    end
+
+    context "when there are notification addresses" do
+      before do
+        server.organization.users << create(:user)
+      end
+
+      it "sends an email" do
+        server.suspend("some reason")
+        delivery = ActionMailer::Base.deliveries.last
+        expect(delivery).to have_attributes(subject: /server has been suspended/i)
+      end
+    end
+  end
+
+  describe "#unsuspend" do
+    let(:server) { create(:server, :suspended) }
+
+    it "removes the suspension time" do
+      expect { server.unsuspend }.to change { server.reload.suspended_at }.to(nil)
+    end
+
+    it "removes the suspension reason" do
+      expect { server.unsuspend }.to change { server.reload.suspension_reason }.to(nil)
+    end
+  end
+
+  describe "#ip_pool_for_message" do
+    context "when the message is not outgoing" do
+      let(:message) { MessageFactory.incoming(server) }
+
+      it "returns nil" do
+        expect(server.ip_pool_for_message(message)).to be nil
+      end
+    end
+
+    context "when a server rule matches the message" do
+      let(:domain) { create(:domain, owner: server) }
+      let(:ip_pool) { create(:ip_pool, organizations: [server.organization]) }
+      let(:message) do
+        MessageFactory.outgoing(server, domain: domain) do |msg|
+          msg.rcpt_to = "hello@google.com"
+        end
+      end
+
+      before do
+        create(:ip_pool_rule, ip_pool: ip_pool, owner: server, from_text: nil, to_text: "google.com")
+      end
+
+      it "returns the pool" do
+        expect(server.ip_pool_for_message(message)).to eq ip_pool
+      end
+    end
+
+    context "when an org rule matches the message" do
+      let(:domain) { create(:domain, owner: server) }
+      let(:ip_pool) { create(:ip_pool, organizations: [server.organization]) }
+      let(:message) do
+        MessageFactory.outgoing(server, domain: domain) do |msg|
+          msg.rcpt_to = "hello@google.com"
+        end
+      end
+
+      before do
+        create(:ip_pool_rule, ip_pool: ip_pool, owner: server.organization, from_text: nil, to_text: "google.com")
+      end
+
+      it "returns the pool" do
+        expect(server.ip_pool_for_message(message)).to eq ip_pool
+      end
+    end
+
+    context "when the server has no default pool and no rules match the message" do
+      let(:domain) { create(:domain, owner: server) }
+      let(:message) { MessageFactory.outgoing(server, domain: domain) }
+
+      it "returns nil" do
+        expect(server.ip_pool_for_message(message)).to be nil
+      end
+    end
+
+    context "when the server has a default pool and no rules match the message" do
+      let(:organization) { create(:organization) }
+      let(:ip_pool) { create(:ip_pool, organizations: [organization]) }
+      let(:server) { create(:server, organization: organization, ip_pool: ip_pool) }
+      let(:domain) { create(:domain, owner: server) }
+      let(:message) { MessageFactory.outgoing(server, domain: domain) }
+
+      it "returns the server's default pool" do
+        expect(server.ip_pool_for_message(message)).to eq ip_pool
+      end
+    end
+  end
+
+  describe ".[]" do
+    context "when provided with an integer" do
+      it "returns the server with that ID" do
+        server = create(:server)
+        expect(described_class[server.id]).to eq server
+      end
+
+      it "returns nil if no server exists with the ID" do
+        expect(described_class[1234]).to be nil
+      end
+    end
+
+    context "when provided with a string" do
+      it "returns the server that matches the given permalinks" do
+        server = create(:server)
+        expect(described_class["#{server.organization.permalink}/#{server.permalink}"]).to eq server
+      end
+
+      it "returns nil if no server exists" do
+        expect(described_class["hello/world"]).to be nil
+      end
+    end
+  end
+end
diff --git a/spec/app/models/user_spec.rb b/spec/models/user_spec.rb
similarity index 100%
rename from spec/app/models/user_spec.rb
rename to spec/models/user_spec.rb
diff --git a/spec/app/models/worker_role_spec.rb b/spec/models/worker_role_spec.rb
similarity index 100%
rename from spec/app/models/worker_role_spec.rb
rename to spec/models/worker_role_spec.rb
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index b46a817..4a5d93e 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -9,6 +9,7 @@ require "factory_bot"
 require "timecop"
 require "database_cleaner"
 require "webmock/rspec"
+require "shoulda-matchers"
 
 DatabaseCleaner.allow_remote_database_url = true
 ActiveRecord::Base.logger = Logger.new("/dev/null")
@@ -16,8 +17,17 @@ ActiveRecord::Base.logger = Logger.new("/dev/null")
 Dir[File.expand_path("factories/*.rb", __dir__)].each { |f| require f }
 Dir[File.expand_path("helpers/**/*.rb", __dir__)].each { |f| require f }
 
+ActionMailer::Base.delivery_method = :test
+
 ActiveRecord::Migration.maintain_test_schema!
 
+Shoulda::Matchers.configure do |config|
+  config.integrate do |with|
+    with.test_framework :rspec
+    with.library :rails
+  end
+end
+
 RSpec.configure do |config|
   config.use_transactional_fixtures = true
   config.infer_spec_type_from_file_location!
diff --git a/spec/app/services/unqueue_message_service/incoming_messages_spec.rb b/spec/services/unqueue_message_service/incoming_messages_spec.rb
similarity index 100%
rename from spec/app/services/unqueue_message_service/incoming_messages_spec.rb
rename to spec/services/unqueue_message_service/incoming_messages_spec.rb
diff --git a/spec/app/services/unqueue_message_service/outgoing_message_spec.rb b/spec/services/unqueue_message_service/outgoing_message_spec.rb
similarity index 100%
rename from spec/app/services/unqueue_message_service/outgoing_message_spec.rb
rename to spec/services/unqueue_message_service/outgoing_message_spec.rb
diff --git a/spec/app/services/unqueue_message_service_spec.rb b/spec/services/unqueue_message_service_spec.rb
similarity index 100%
rename from spec/app/services/unqueue_message_service_spec.rb
rename to spec/services/unqueue_message_service_spec.rb
diff --git a/spec/app/services/webhook_delivery_service_spec.rb b/spec/services/webhook_delivery_service_spec.rb
similarity index 100%
rename from spec/app/services/webhook_delivery_service_spec.rb
rename to spec/services/webhook_delivery_service_spec.rb