diff --git a/app/lib/received_header.rb b/app/lib/received_header.rb
new file mode 100644
index 0000000..7d578f4
--- /dev/null
+++ b/app/lib/received_header.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+class ReceivedHeader
+
+  OUR_HOSTNAMES = {
+    smtp: Postal.config.dns.smtp_server_hostname,
+    http: Postal.config.web.host
+  }.freeze
+
+  class << self
+
+    def generate(server, helo, ip_address, method)
+      our_hostname = OUR_HOSTNAMES[method]
+      if our_hostname.nil?
+        raise Error, "`method` is invalid (must be one of #{OUR_HOSTNAMES.join(', ')})"
+      end
+
+      header = "by #{our_hostname} with #{method.to_s.upcase}; #{Time.now.utc.rfc2822}"
+
+      if server.nil? || server.privacy_mode == false
+        hostname = DNSResolver.local.ip_to_hostname(ip_address)
+        header = "from #{helo} (#{hostname} [#{ip_address}]) #{header}"
+      end
+
+      header
+    end
+
+  end
+
+end
diff --git a/app/lib/smtp_server/client.rb b/app/lib/smtp_server/client.rb
index 3040f7f..c89aea2 100644
--- a/app/lib/smtp_server/client.rb
+++ b/app/lib/smtp_server/client.rb
@@ -366,8 +366,8 @@ module SMTPServer
       @headers = {}
       @receiving_headers = true
 
-      received_header = Postal::ReceivedHeader.generate(@credential&.server, @helo_name, @ip_address, :smtp)
-                                              .force_encoding("BINARY")
+      received_header = ReceivedHeader.generate(@credential&.server, @helo_name, @ip_address, :smtp)
+                                      .force_encoding("BINARY")
 
       @data << "Received: #{received_header}\r\n"
       @headers["received"] = [received_header]
diff --git a/app/models/incoming_message_prototype.rb b/app/models/incoming_message_prototype.rb
index 334df62..ee3c0ec 100644
--- a/app/models/incoming_message_prototype.rb
+++ b/app/models/incoming_message_prototype.rb
@@ -95,7 +95,7 @@ class IncomingMessagePrototype
           content: attachment[:data]
         }
       end
-      mail.header["Received"] = Postal::ReceivedHeader.generate(@server, @source_type, @ip, :http)
+      mail.header["Received"] = ReceivedHeader.generate(@server, @source_type, @ip, :http)
       mail.to_s
     end
   end
diff --git a/app/models/outgoing_message_prototype.rb b/app/models/outgoing_message_prototype.rb
index 7362f30..f36522a 100644
--- a/app/models/outgoing_message_prototype.rb
+++ b/app/models/outgoing_message_prototype.rb
@@ -177,7 +177,7 @@ class OutgoingMessagePrototype
           content: attachment[:data]
         }
       end
-      mail.header["Received"] = Postal::ReceivedHeader.generate(@server, @source_type, @ip, :http)
+      mail.header["Received"] = ReceivedHeader.generate(@server, @source_type, @ip, :http)
       mail.message_id = "<#{@message_id}>"
       mail.to_s
     end
diff --git a/lib/postal/received_header.rb b/lib/postal/received_header.rb
deleted file mode 100644
index b019d69..0000000
--- a/lib/postal/received_header.rb
+++ /dev/null
@@ -1,32 +0,0 @@
-# frozen_string_literal: true
-
-module Postal
-  class ReceivedHeader
-
-    OUR_HOSTNAMES = {
-      smtp: Postal.config.dns.smtp_server_hostname,
-      http: Postal.config.web.host
-    }.freeze
-
-    class << self
-
-      def generate(server, helo, ip_address, method)
-        our_hostname = OUR_HOSTNAMES[method]
-        if our_hostname.nil?
-          raise Error, "`method` is invalid (must be one of #{OUR_HOSTNAMES.join(', ')})"
-        end
-
-        header = "by #{our_hostname} with #{method.to_s.upcase}; #{Time.now.utc.rfc2822}"
-
-        if server.nil? || server.privacy_mode == false
-          hostname = DNSResolver.local.ip_to_hostname(ip_address)
-          header = "from #{helo} (#{hostname} [#{ip_address}]) #{header}"
-        end
-
-        header
-      end
-
-    end
-
-  end
-end
diff --git a/spec/lib/postal/received_header_spec.rb b/spec/lib/received_header_spec.rb
similarity index 98%
rename from spec/lib/postal/received_header_spec.rb
rename to spec/lib/received_header_spec.rb
index 0a9c6bb..199f027 100644
--- a/spec/lib/postal/received_header_spec.rb
+++ b/spec/lib/received_header_spec.rb
@@ -2,7 +2,7 @@
 
 require "rails_helper"
 
-describe Postal::ReceivedHeader do
+describe ReceivedHeader do
   before do
     allow(DNSResolver.local).to receive(:ip_to_hostname).and_return("hostname.com")
   end