[plug] anti-spam + postfix

[Luke Dudney]

On Tue, 2003-06-10 at 11:17, Ben Jensz wrote:
> Hey all,
> 
> I'm looking at ways to try and close a loophole that is being used to 
> still spam users on our mail server.
> 
> The problem is that the spammers are using the relay mail server 
> operated by our ISP that is set to accept mail for our domain(s) (in 
> case our mail server goes down) to relay spam through to us, hence 
> evading maps_rbls rejections as the client delivering the mail to our 
> mail server is our ISPs relay mail server and not the one that would get 
> bounced by the maps_rbls rejections.
> 
> Any suggestions for overcoming this problem?  I have considered just 
> removing the ISP relay server as a backup mx, but thats really not 
> desirable or practical at all....
> 
> TIA for any suggestions.
> 
> Cheers,
> 
> 
> Ben
> 
> 


I have never used it but it is my understanding that SpamAssassin can
consult DNSRBLS based on the IPs in the Received: lines of the emails.
This would let you do DNSRBL lookups on the client that connected to
your ISP's mail server.

Cheers
Luke