backscatter by DSN: Service unavailable

Ronny T. Lampert telecaadmin at
Thu Jan 31 08:56:39 GMT 2008

>> The cleanest solution would be to talk with those subdomain admins and
>> try to improve your frontend up to a level they will gladly accept.
> So many people, so many systems, changing every month...

Well, what can I say ... University at its best :o)
Guess you should get together with them on a more personal level and try 
to improve the situation. And afterwards present to the problem and a 
possible solution with estimate to your boss.

>> The quickest solution is to try and reduce the bounces by doing some
>> kind of milter-ahead solution; this will maybe reduce the backscatter by
> I thought milter ahead will reduce backscatter from DSN send because of
> not existing wrong rcpt to: messages (Am I wrong here?).
> Those are not the problem at the moment.
> I get spammy non-conformous mail_from domains (valid A record , invalid MX) that
> my sendmail 8.13.8 relays but other postfixes may not. Also DNS name resolution
> might differ between different servers.

Only partially wrong :)
With milter-ahead you can reduce the backscatter of mail from: <...> 
rejections, because you will first ask the accepting mail server "will 
you accept a mail, from: -> to: ?".

Or you could just ditch sendmail and use postfix with a similar 
rejection policy instead?


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