Since this morning I have received over 400 spam messages at my corporate email address, over 100 of them claiming to be telling me that email messages I've sent have been returned as undeliverable. I haven't actually sent any of these. Knowing that messages can have been generated on my machine by malware I've just scanned the hard drive for viruses and it comes up clean.

Anyone have any ideas? Anyone else currently having a similar experience?

Your email address appears to be in the hands of a spammer. There are thousands of emails going out with your address as the reply-to. When an email hits a non-working account on a particular server an undeliverable message is sent out (to the reply-to). Aside from the 100 undeliverable messages, what do the others say? Are they responses (auto-generated or not) to spam? One possible explanation...

All the ones I've seen have been auto-generated.

Do you mean that you have independent knowledge that someone is sending emails as if from me, or you're surmising that that's the reason? A major difference. If it really is the former, what can I do about it?

pedro2, do more virus scans/searches.. I had a similar thing happen to me recently. Turned out I had a trojan horse that sent an email to every email address in my contact list and also wiped out my contact list!!
My friend told me to scan my pc with the top five virus scans listed on a google search of 'free virus scan'. I believe that it was http://www.kaspersky.com/virusscanner that identified the virus I had. Several others, including the one I paid money for on my laptop did not identify the trojan horse.
Good luck..

PS The email that was sent out did not include any virus, thankfully.

Damn, I wish there was a way to track these guys down and feed them exactly what they give us.

Knckr has it correct....most likely. Spammer spoofing your email addy as sender. Not much you can do P1, except be happy with the knowledge it's only 400.

P2 actually.....

I don't recognise any of the addresses which have replied to me - none of them is from my address book.

ooppps my bad. fat fingers.

There's the proof.,..spammer! Not a trojan. Not much you can do.....happens every day here to the tune 1000's a week with my elists.
Make your lifer simpler. Create a mail filter and direct all those Mailer-Daemon, etc., right to the junk box.

That is in effect where they're going, but because I get emails from all sorts of strange people (!) I have to scan the junk before I delete it. That's how I saw all this stuff. I already knew I probably had a problem from the time it took for my email to download. I've had another 30 since I first posted about it.

What's the intention with this stuff? There's no obvious theft or fraud opportunity, and I don't believe these people are motivated by the desire just to make a nuisance of themselves.

P2, it is possible that the spam is originating on your machine too - aka you have a spambot on your computer. Easy way of checking (but not foolproof) is to open up a command prompt (start->run, type cmd), type "netstat -a" then enter. This shows all of the active connections on your machine. If you see more/suspicious connections there, especially numerous SMTP connections to random mail servers, then you have a spambot.

The motivation is to use a *valid* email address to get through spam filters out on the internet. It is likely that the spammer is using the smtp.btl.net server to relay the spam off of... All sorts of possibilities here. Not that it would solve this problem, but using a local mail client (e.g. outlook) is the cause of mucho problems. You want sanity (most of the time), switch to GMAIL - and use the web client - and YES you can keep the same email address.