From: Mikel Lindsaar <raasdnil@...>
Date: 2008-04-06T10:49:03+09:00
Subject: Re: ActionMailer Message-Id field

>  >  delivered via ActionMailer.  The underlying TMail object allows the
>  >  message_id to be set, but it looks like the deliver method of action
>  >  mailer will overwrite any value that is presently there at the time of
>  >  delivery.
>  I'm wondering if there's a legitimate use case for this.  The one
>  reason I can think of for doing this is to forge an untraceable
>  message-id on a spam e-mail.

It is a good default action as you want every email to have a unique
message_id, in fact, you need to have a unique message id per the
RFCs.

Unfortunately, ActionMailer does this as a forced default, perhaps the
OP could submit a patch which simply says:

 mail.add_message_id unless mail.message_id

That would then only add a message ID if the mail did not already have
one. That would probably work in most cases, but you would have to
look at the consequences of replying to messages etc and handle those,
you need to ensure that you know what message ids are unique and not.

Regards

Mikel Lindsaar
TMail Maintainer