Great Circle Associates List-Managers
(May 2002)

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Subject: Re: large ISPs blocking mailing lists
From: Sean Brunnock <brunnock @ server . com>
Date: Sat, 18 May 2002 12:22:55 -0400
To: "list-managers @ greatcircle . com" <list-managers @ greatcircle . com>
In-reply-to: <Pine . BSI . 4 . 40 . 0205181119340 . 1754-100000 @ tom . iecc . com>
References: <3CE627AB . 25283 . 33E007D @ localhost>

At 11:30 AM 5/18/02, "John R Levine" <johnl @
 iecc .
 com> wrote:
Yes, indeed.  That's because their servers are melting down from the
torrents of spam and they're desperate.  I know several of them, this is
what they tell me.

I'd take their whines with a grain of salt.

Spammers love to use "" as a fake host to stick in their headers
in order to cover their tracks. Over the years, we've received tons of bounces
and complaints about spam allegedly from us.

For years,'s MX was hosted by an ISP in Massachusetts. They
had been an ISP for years, had decent admins and a robust infrastructure. 

Last year, they panicked because someone sent large amounts of spam
to nonexistent  AOL accounts and they were getting hammered by bounces.
The ISP simply erased our MX record (they handled our NS as well) and all 
of the email went to "" which was our main webserver. Thousands 
of bounce messages started flowing in. 

Our server held up fine. The load average didn't even go over 2.0. I called the
ISP and asked what the big deal was. He replied that the storm must be 
over and he put the MX record back in. An hour later, he took it out. Again
I explained to him that my one server which was doing double duty was
handling the bounces just fine. When it got through the backlog, the load
average went to less than 1. 

He couldn't believe it. He got the email admins together and they went over
the multiple email servers, fine tuned them, pronounced the problem solved
and put the MX back in. They lasted two hours this time.

The problem was they were using an MTA which would accept all messages
and spool them. The servers were croaking from all of the bogus bounce 
messages in their queue. I was using Sendmail which would bounce messages
for bogus users without accepting them. They wouldn't believe me though.
They insisted that MTAs had to accept messages and spool them. 

Sean Brunnock

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