[Email-SIG] email v3.0 feature request

[Matthew Dixon Cowles]

Dear Gerrit,

> I think it may be useful if the e-mail module can treat the
> Received:-headers specially, and parse them for the user.

I agree that doing that would be useful but I've looked at doing it
outside of the email module and I think it would be pretty hard.

The problem is that RFC 2822 allows a rather elaborate syntax in
received headers which I think would be at least a big nuisance to
parse. Here's a small example:

    The "Received:" field contains a (possibly empty) list of
    name/value pairs followed by a semicolon and a date-time
    specification.  The first item of the name/value pair is defined
    by item-name, and the second item is either an addr-spec, an
    atom, a domain, or a msg-id.

And it gets worse from there. All of the really interesting
information in a received header is in parentheses. Those are
technically comments not specified by the syntax above. And comments
are nearly free-form. So you'd need to try to match against what you
think that every popular MTA generates and then probably try a few
other things besides. That sort of moving target would create a lot
of maintenance work.

D. J. Bernstein has more on the subject at:

http://cr.yp.to/immhf/envelope.html

> It is just an idea. I have no plans to implement it.

Rats!

Regards,
Matt