Re: [Exim] Reject an email with a user-defined message

Odhiambo Washington wrote:
> You must be talking about the system_filter.

Nope. Two possible ways of integrating a virus checker into Exim is to either
use a pipe transport through to the virus checker which then squirts clean
messages back to Exim with the -oMr option. The problem with this is that
virus checker has to extract the local recipients from the headers (easy
enough, 49 line sh/awk script). However, with mailing lists (such as Exim
users), the recipient is *not* listed in the headers, instead being solely
listed in the envelope (who appears after the RCPT TO does not have to appear
in To:, Cc: or Bcc: at all). This is the same problem with using, say,
fetchmail to collect mail from a POP3 host for a unix system.

But if the message does not *leave* Exim, but instead is scanned while the
message is still in the queue then this problem is avoided. With the former
system, any errors or virus warnings can simply be written on the stdout by
the scanning program and Exim will return that as an error message to the
original sender. With the latter system, the queue scanner has to remove the
message manually.

Why don't I hack Exiscan to use the virus checker we're using. Dunno. I'm
still understanding how Exiscan works, which is an achievement given I've
never written a #!/usr/bin/perl of perl.

A third way would be to call the scanning program from the system filter, but
calling external programs from a filter I've not learnt to do yet. Much
research awaits...
--
Mike Kenyon <mike@???> | Tel: +44 (0) 1902 376351
I.T. Manager for David Austin Roses Ltd | Fax: +44 (0) 1902 372142