[Mimedefang] Greylisting

Brian Leyton bleyton at cpe-corp.com
Thu Dec 15 12:15:28 EST 2005

Paul Whittney wrote:
> One other major problem I've run into, is ISP's providing 
> additional MX records in the DNS. So the spam systems that 
> follow the "If the first attempt to send email fails, try the 
> next MX" happens, then the ISP sends it on, which will make 
> it past the blacklist, and if the ISP is whitelisted by IP 
> alone, means the spam gets in.

I know that this might not work for everyone, but for this very reason, I
removed my ISP's mailservers as a secondary MX.  I figure that if my
mailserver or Internet connection is down, then the mail will simply queue
up at the sending server, and retry.  Once my server comes back up, it will
get delivered.  It doesn't buy me much to have my ISP queue up all of that
mail, except for all of the extra spam that comes through the back door.
This has eliminated that particular problem, and made my DNSBLs more
effective.  I still have stuff that makes its way through forwarders like
Bigfoot, but MIMEDefang does a nice job with those.

Brian Leyton
IT Manager
Commercial Petroleum Equipment

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