postmaster@mydomain.com emails in my queue

[BigFunkyChief]

I have a sort of simple question, hopefully I explain it correctly....in my Exchange 2003 queue, I see random emails from 'postmaster@mydomain.com' stuck in queue, they expire after a little while, but I'm not sure why they are there. They're addressed to different, random domains like "abckids.co.uk", "doneasy.com", a few from "webscape.net", etc, and random users from these domains. Get about 10 a day.

The different queue info messages for the domains are "The server did not respond to a connection attempt" and "unable to bind to the destination server in DNS".

We're running DNS forwarders to our ISP's DNS server, running Exchange 2003 on SBS, with SP1. Thanks!

 

[fs483]

Probably NDRs. I disable all NDRs on my servers.

 

[BigFunkyChief]

That makes sense. Wouldn't you want NDRs enabled, so that if you send an email to someone and mistype their address, the user will get a delivery failure back?

 

[fs483]

Normally yeah, but when your server gets hit by a dictionary attack then your domain starts receiving HUGE amounts of junk or spam emails. Meanwhile your system is busy trying to reply saying that emailaddress@yourdomain.com doesn't exist. Most of the domains that your server is trying to recontact probably don't exist so either because they are spoofed or randomly generated. All this can cause your server to try endlessly until it times out.

 

[BigFunkyChief]

Thanks for the advice...I think I'll do that.