Spam Problem

[PaulBarron]

I have Exchange 5.5 running on Windows NT 4 server.

Suddenly in my Internet Mail Connector in the Outbound Messages awaiting delivery, this is being bombarded with spam emails and I can't seem to stop it. I am getting literally hundreds per minute!

Nothing has been changed on the server to my knowledge. Can anyone offer an explanation/solution?

 

[quell]

faq10-1779
thread10-540298
If you already have some sort of spam settings enabled then read this.

This info was posted in another post from bronc:
REGUARDING THE <> E-MAILS IN OUTBOUND QUE:

I'll tell you what I've found this to be 90% of the time and it's not open relay:

1) Spammer finds out about your domain, let's COMPANY.COM (this isn't hard to do as domain names are public knowledge)

2) Spammer sends mail(s) to some arbitrary name at COMPANY.COM that winds up being invalid. Of course, the Spammer sends this email using a bogus return address.

3) Exchange accepts the mail, since it's sent to the proper domain name, then discovers that the actual user part is not valid.

4) Exchange uses the bogus return address to try and send an NDR. At the same time, Exchange strips away the sender address, leaving it as <>. This is done to prevent Exchange from going into an endless loop, as it would be constantly reporting back to itself that it's own NDR was undeliverable.

5) Eventually, these messages time out in the queue and should be deleted.