The Message-ID as specified by rfc822 is supposed to be a unique identifier for that individual email. That makes it an ideal tracking token for debugging and forensics, just like X-Request-Id does for web request.

If an inbound email does not, against the rfc822 mandate, specify a Message-ID, one will be generated using the approach from Mail::MessageIdField.

Methods

Instance Public methods

create_and_extract_message_id!(source, **options)

Create a new InboundEmail from the raw source of the email, which is uploaded as an Active Storage attachment called raw_email. Before the upload, extract the Message-ID from the source and set it as an attribute on the new InboundEmail.

📝 Source code
# File actionmailbox/app/models/action_mailbox/inbound_email/message_id.rb, line 16
    def create_and_extract_message_id!(source, **options)
      message_checksum = OpenSSL::Digest::SHA1.hexdigest(source)
      message_id = extract_message_id(source) || generate_missing_message_id(message_checksum)

      create! raw_email: create_and_upload_raw_email!(source),
        message_id: message_id, message_checksum: message_checksum, **options
    rescue ActiveRecord::RecordNotUnique
      nil
    end
🔎 See on GitHub

create_and_upload_raw_email!(source)

📝 Source code
# File actionmailbox/app/models/action_mailbox/inbound_email/message_id.rb, line 37
      def create_and_upload_raw_email!(source)
        ActiveStorage::Blob.create_and_upload! io: StringIO.new(source), filename: "message.eml", content_type: "message/rfc822",
                                               service_name: ActionMailbox.storage_service
      end
🔎 See on GitHub

extract_message_id(source)

📝 Source code
# File actionmailbox/app/models/action_mailbox/inbound_email/message_id.rb, line 27
      def extract_message_id(source)
        Mail.from_source(source).message_id rescue nil
      end
🔎 See on GitHub

generate_missing_message_id(message_checksum)

📝 Source code
# File actionmailbox/app/models/action_mailbox/inbound_email/message_id.rb, line 31
      def generate_missing_message_id(message_checksum)
        Mail::MessageIdField.new("<#{message_checksum}@#{::Socket.gethostname}.mail>").message_id.tap do |message_id|
          logger.warn "Message-ID couldn't be parsed or is missing. Generated a new Message-ID: #{message_id}"
        end
      end
🔎 See on GitHub