The existing relaying controls in Exim (described in section 42.5 of
the manual) use only the originating host to determine what messages
will be accepted for relaying outside local_domains + relay_domains.
I think it would be useful to be able to have a test on (envelope)
sender available as well. I want to able to implement a rule like:
on the *.cus.cam.ac.uk machines
accept mail from anywhere if it is for *@cus.cam.ac.uk
accept locally generated mail for anywhere
accept mail from other machines in the 131.111.*.* net
for anywhere but ONLY if the envelope sender is
*@cus.cam.ac.uk
reject anything else
The last situation is meant to be for imap/pop MUAs on workstations
configured to use cus.cam.ac.uk as a server. The advantage of the
envelope sender being in local_domains is that (with sender_verify
on) we can check that the account is valid and error reports at least
putatively deliverable.
Philip has expressed doubts about this, on the basis that the envelope
sender can so easily be forged. I still think that it would be useful
to force the punters to forge a valid address rather than an invalid one!
Chris Thompson Cambridge University Computing Service,
Email: cet1@??? New Museums Site, Cambridge CB2 3QG,
Phone: +44 1223 334715 United Kingdom.
