Colin Keith wrote:
> Hi,
> 
> Like lots of people I've having a hard time with spammers misusing my
> customer's sites and services....

*snip*

> 
> Does any one have any suggestions?

Keeping in mind that once you have tamed/armored Exim, you still have to 
get control over smtp-outbound capable executables and such within in 
your clients' other apps.  These do not even need to get near Exim, nor 
require privileged ports or UID:GID either....

Ergo, life will be much simpler if you segregate the services by 
platform and IP:

- do not permit any services 'other than' an all-virtual-user MTA on one 
'server' (no local accounts).

- permit NO mail services on another 'server' - say one with web sites.

The webish one (or external fw) should block any outbound traffic 
destined for port 25.

It *could* permit logging-in to its sibling on port 587 for controlled 
smarthost use. At that point, cron jobs aside, there are no longer any 
'non-smtp' sessions, so the normal AUTH and smtp session acl's apply.

Use of virtualized 'servers' means you do not necessarily need two 
physical boxen - though I'd still recommend it.

Anything else gets MORE complex, and harder to debug, protect, and stay 
abreast of, as you are just beginning to detail.

HTH,

Bill


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