refactor: move lib/postal/received_header to app/lib/received_header

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