From:, Mail, and sendmail

[Guy Harris]

> From: phil at amd.UUCP (Phil Ngai)

> When mail passes through a non-sendmail site, the From: line
> is not updated and becomes incorrect. But Berkeley Mail uses
> it to form the return address if you do a "r" command.

> From: dave at uwvax.ARPA

> You will notice (if you have source) that 4.2bsd Mail will take
> the 'Reply-to:' field instead of 'From:' if the former exists.

We deal with it by using path aliasing and sending mail to "joeblow at foo.UUCP".
Most of the time, that works; when it doesn't, the user does have to
construct the path themselves (using ~h to monkey with the "To:" field),
but that's fairly rare.

"Reply-to:" was, I believe, intended for use with messages sent to
distribution lists, so the whole list wouldn't see the replies, so it isn't
a solution to the problem.  Besides, the non-"sendmail" sites aren't likely
to properly update "Reply-to:" if they don't update "From:".  The problem
is somewhat one of relative (UUCP "bang") vs. absolute addressing.  I
shouldn't have to know or care how a mail message got here; getting a reply
back is the responsibility of the mail system.  Hopefully, the UUCP project
will clear up these problems, at least for participating sites.

> A side point.  If the non-BSD site messes up the 'From:' line,
> shouldn't the site in question be notified of their actions?

Yes, if you consider RFC822 compliance to be everybody's responsibility and
you consider not properly updating the "From:" field to imply non-compliance
with 822.  However, not everybody out there can get "sendmail" (it's not
a BSD vs. non-BSD question; lots of non-BSD sites run "sendmail") and not all
of them are really better off going through the trouble to get and run
"sendmail" (it does impose a cost - see the paper on 4.2BSD performance from
Leffler, McKusick, et. al. from the SLC USENIX).

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy