What does this email mean >> ezmlm warning

I got this email today, I can’t figure out if its just an attempt for a spammer to see if my email address is active, or if someone is spoofing my address. I checked usenet, and found a bunch of similar messages, but no explanation of it. Anywhere, here’s the email (I took out my email address):

Spamhaus is an anti-spam web site. They maintain a database of known spammers that many email service providers use to block spam. So what the report is saying is that the original email was bounced because it came from a suspected spammer.

The crux of the matter is; what’s the dm-pd21 mailing list? If you know what that is, and want to remain on it, then you’re going to have to sort things out. If you’ve never heard of the list, and don’t want to be on it, then spamhaus is doing its job. Ignore the email, it’s spam.

The only other possibility is that it’s yet another complicated email loophole that someone is trying to exploit to generate spam. And to be smart they’re spoofing spamhaus involvement. But it goes without saying, don’t reply.

I just assumed that the spamhaus link was spoofed. I have no idea what that mailing list is for – I don’t get any lists sent to that particular email address.

Anyway, I’ll take your advice and not respond. I have a feeling that if I do, I’ll end up with an extra 10 spams a day.