Sapm control from relaying allowed clients (out bound spam)

[osman]

Hi Everybody,

I have controlled spam for domains defined in mailserver(virtual/local domains), ive used sendmail and qmail with spamassassin.

These mail servers also allow relaying for many local ips, as its a ISP setup.

Sometimes some clients send thousands of mails to many destinations it causes our servers to be black listed.

Is there any way i can filter the mails coming from my clients/relaying allowed ips ? or i can set up limits per ip.

Any combination of mailserver + any software will work.

Regards
osman