On Fri, 8 Mar 2002, Dave C. wrote:
> Why is there no acl that runs after mail from?
Because I discovered, in the early days of Exim, that there are MTAs out
there that don't treat 5xx errors after MAIL commands as show stoppers.
They just try to resend the message later. Exim 3 ended up with a
complicated scheme of refusing after DATA the first time (so as to log
the header), refusing after MAIL the second time (because that seemed
the next best thing), and refusing each RCPT for the third attempt.
These stages got added as we discovered actual MTA behaviour.
For Exim 4, I didn't want to encourage refusals of MAIL commands,
because it doesn't always work. The best known way to say "no" to an MTA
is to refuse every RCPT. (Of course, there are some checks you can't do
till after DATA, so I had to make that available, but you run the risk
of getting repeated attempts.)
> I would like to issue a 5xx right after MAIL FROM: under certain
> conditions, yet I can't seem to find a way to do that..
If you really want to do that, it is not a huge amount of work to add
the code, but I would strongly advise you to think carefully about this.
Philip
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
