>Dicionary attack. They are trying to find an account to use. >IP addresses are not in the same class c so it makes it hard to >block.
They are probably using open relays, so that's impossible to block since there are at least several 100K open relays. Very hard to defend against a DoS on the target box, since execution of the defense itself becomes part of the exhaustion of resources. IMGate, subscribed to RBL servers and using other tactics, moves the defense and DoS to an upstream box, so the target mailbox server, and your users, don't feel the DoS at all. IMGate has lots of other advantages besides DoS defense. :)) Len www.menandmice.com/DNS-training : DNS Training BIND8NT.MEIway.com : ISC BIND for NT4 & W2K IMGate.MEIway.com : Build free, hi-perf, anti-abuse mail gateways Please visit http://www.ipswitch.com/support/mailing-lists.html to be removed from this list. An Archive of this list is available at: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Please visit the Knowledge Base for answers to frequently asked questions: http://www.ipswitch.com/support/IMail/
