Hello,
The central mailhub here mainly acts as a gateway (mail server?) in that it
receives mail for the University's users but sends most of it onto other
file servers. The rest of the mail goes off-site. Extremely little - in fact
only for one account - is delivered 'local' to the mailhub itself.
We have for a short time now been having problems with a Microsoft Exchange
server in another section of the Uni. Mail is sent to it from the mailhub
(the message originating from anywhere else), using a smartuser director,
and it arrives at the Exchange system. A 'delivery notification' (if
requested) is sent by the system back to the 'Return-path:' address. But in
all cases this is 'postmaster@???' since although the exim
process sends the message, mail for 'exim' is aliased in /etc/aliases to
postmaster. I assume then that it is exim which is setting the SMTP MAIL
FROM address of 'postmaster@???', and the exchange server sees
this and uses it to write in a Return-path: header.
This is, obviously, not quite right - delivery notifications shouldn't being
going to the postmaster. By default exim (3.03) has the 'return_path_remove'
option set. So the exchange server will not see any other Return-path:
header (we don't set it on the non-local transports at present). However, if
we set the Return-path: header on the out-going mail SMTP transport and set
it to the original $sender_address (?). The exchange server *may* see the
header and ignore the MAIL FROM address - this needs testing of course. My
question though is is this correct? What do others do, if anything, about
this? Should I be doing this?
Reading RFC's 822, 2076 and the latest drums (smtpupd) report seem to
confuse things a bit more since they seem to indicate that the Return-path:
header should be used for mail delivery errors and non-delivery
notifications. They do not say to use it for delivery notifications, but
likewise don't seem to say what should be used.
I would add that we only seem to have the problem with this one Exchange
server, yet I assume we are receiving/sending mail to other servers around
the world and that the senders are requesting delivery receipts. The
postmaster account is not receiving those recipts. That made it look as if
this one server was mis-configured, but looking at the Return-path: header
in the RFC's seems to have confuised things even more!
Any help or thoughts appreciated,
John.
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John Horne, University of Plymouth, UK Tel: +44 (0)1752 233914
E-mail: jhorne@???
Finger for PGP key: john@???
