On Mon, 22 Dec 2003, Don Walker wrote:
> My Exim 4.20 receives mail for a user whose mail is forwarded from another
> service with a constant ip address (1st 3 octets), thereby negating my
> normal dns blacklist spam blocking measures. However, the ip address which
> sent the message to the forwarding service is within the headers. I'm
> wondering if/how I can extract that ip address and use it to check against
> dns blacklists.
Sorry, I don't know the answer to your question.
If you do find the answer, watch out in case the forwarding service
is also the smarthost for dial-up lines from the same provider.
In that case it would be correct for the address in the
last-but-one received from line to appear in DUL blacklists.
Worse, if you run exiscan, any mail you reject for this user will
turn into a *bounce* from the forwarding service, and you may find
that innocent third parties receive spam or viruses intended for
that user.
I've come to the conclusion that it is almost impossible to be more
selective in what you accept at SMTP time than the forwarding
service. :-(
--
Dr. Andrew C. Aitchison Computer Officer, DPMMS, Cambridge
A.C.Aitchison@??? http://www.dpmms.cam.ac.uk/~werdna
