[exim] Help with our postmaster@my.domain being spoofed as a…

Hi

Having searched the exim mail archives and not found my problem there I
thought of asking the experts.

I am postmaster for a local company mail server (it is running Exim
4.63) that receives its e-mail from our company mail relay which does
the virus checking of the e-mail as it arrives into the company.

We have a lot of e-mail arriving for users that have left the company
and so I created a reject-list file which is checked in the
acl_smtp_rcpt acl so that these e-mails are rejected early which saves
on downloading them and running them through Spamassassin (use sa-exim).

This works fine for most of this type of spam.

But lately, an increasing percentage of this spam is arriving with the
sender spoofed to be postmaster@??? (i.e. me) and when Exim issues
a deny because the recipient has left I then get an e-mail from the
postmaster of our company mail relay sent to postmaster@??? to
inform me that the e-mail to jbloggs@??? failed because of unknown
user!


How can I reject this type of spam without getting the e-mail from
postmaster of our company mail relay?

Would my only option to stop this happening be to accept these e-mails
(but then I would like to bin it without spam checking it which I'm not
sure is possible when using sa-exim)?


Thanks


Paul McIlfatrick