module ActionMailbox::InboundEmail::MessageId

def create_and_extract_message_id!(source, **options)

it as an attribute on the new +InboundEmail+.
attachment called +raw_email+. Before the upload, extract the Message-ID from the +source+ and set
Create a new +InboundEmail+ from the raw +source+ of the email, which is uploaded as an Active Storage 
def create_and_extract_message_id!(source, **options)
  message_checksum = Digest::SHA1.hexdigest(source)
  message_id = extract_message_id(source) || generate_missing_message_id(message_checksum)
  create! options.merge(message_id: message_id, message_checksum: message_checksum) do |inbound_email|
    inbound_email.raw_email.attach io: StringIO.new(source), filename: "message.eml", content_type: "message/rfc822"
  end
rescue ActiveRecord::RecordNotUnique
  nil
end

def extract_message_id(source) 

def extract_message_id(source)
  Mail.from_source(source).message_id rescue nil
end

def generate_missing_message_id(message_checksum) 

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