postal/app/models/bounce_message.rb

# frozen_string_literal: true

class BounceMessage

  def initialize(server, message)
    @server = server
    @message = message
  end

  def raw_message
    mail = Mail.new
    mail.to = @message.mail_from
    mail.from = "Mail Delivery Service <#{@message.route.description}>"
    mail.subject = "Mail Delivery Failed (#{@message.subject})"
    mail.text_part = body
    mail.attachments["Original Message.eml"] = { mime_type: "message/rfc822", encoding: "quoted-printable", content: @message.raw_message }
    mail.message_id = "<#{SecureRandom.uuid}@#{Postal::Config.dns.return_path_domain}>"
    mail.to_s
  end

  def queue
    message = @server.message_db.new_message
    message.scope = "outgoing"
    message.rcpt_to = @message.mail_from
    message.mail_from = @message.route.description
    message.domain_id = @message.domain&.id
    message.raw_message = raw_message
    message.bounce = true
    message.bounce_for_id = @message.id
    message.save
    message.id
  end

  def postmaster_address
    @server.postmaster_address || "postmaster@#{@message.domain&.name || Postal::Config.postal.web_hostname}"
  end

  private

  def body
    <<~BODY
      This is the mail delivery service responsible for delivering mail to #{@message.route.description}.

      The message you've sent cannot be delivered. Your original message is attached to this message.

      For further assistance please contact #{postmaster_address}. Please include the details below to help us identify the issue.

      Message Token: #{@message.token}@#{@server.token}
      Orginal Message ID: #{@message.message_id}
      Mail from: #{@message.mail_from}
      Rcpt To: #{@message.rcpt_to}
    BODY
  end

end