Re: `user-mail-address' for message-ids

[prj@po.cwru.edu (Paul Jarc)]

"Jason R. Mastaler" <jason@mastaler.com> writes:
> The point is that just because you may not find this functionality
> useful does not mean others do/will not. 

It's more than that: I find it *counter* to usefulness.

> And BTW, it is trivial to make Message-ID the only place your
> hostname would show up in the header.

How are you going to keep it out of the Received field that gets added
*after* the message leaves your computer?  The next SMTP recipient is
typically going to add a Received field with an indication of where
the message came from, and it's not going to trust the sender to
provide that indication; it'll use DNS instead.

> > But their primary purpose is to be a universally unique identifier
> > for messages.  Using the domain from user-mail-address would subvert
> > that purpose.
> 
> No.  Many MUAs use the user's chosen e-mail address (such as Mutt) in
> the message-id instead of the system's fqdn.

I don't know which statement you were trying to refute, but:
- Message-ID's purpose is indeed as I stated.  See RFC822, 4.6.1.
- The behavior you describe does indeed subvert that purpose.  (It
  doesn't guarantee failure, but it encourages it.)

> I say that if the 1st half of the message-id (before the "@")
> doesn't guarantee uniqueness, then we need to rethink the algorithm
> for `message-make-message-id'.

The first part only needs to be unique *on that host*, and
message-make-message-id does a good job of satisfying that
requirement.  But the Message-ID as a whole must be unique
*universally*.  To ensure that, you need to include the host's
identification, and since different hosts may use different methods to
generate the first part, the host's identification must be included in
a universally uniform way, in order to avoid collisions.

> > You already know how to make this change for your own Gnus.  Why do
> > you want to break mine?
> 
> Because if done correctly, it won't "break" anything,

So if hosts don't uniformly embed their own identification into
Message-IDs, and they don't coordinate Message-ID generation, how
would they guarantee uniqueness?  How could it be done "correctly"?


paul