module ActionMailbox::InboundEmail::MessageId

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