Seen the same thing on my old freeserve account - their targeting is RUBBISH - they seem to be going soley on spam-like content (ad/mail lists that ARE legit also get tagged), rather than on the usually unsound source address of most real spam.
Bouncing?
DON'T DO IT - the email address is 99% forged, faked, and often the address of some poor sod who then gets a mailbox full of bounces -
DON'T DO IT.
At best, bouncing email has little or no effect, and at worst, it causes a problem for somebody else who has nothing to do with it.
To avoid spam:
1. Never let your email address be visible in machine-readable form
http://www.clariondeveloper.com/webcloak/index.htm - see this for one way of doing it - though I'm not sure if character encoding is good enough, fragmenting the address in javascript certainly is.
2. Do not use an easily dictionary attackable address - anything 6 characters or less at a popular host is probably already covered.
Use disposable addresses such as spamgourmet if you have to give an address to someone/something you don't trust to respect it.
www.spampal.org
- A fine filter- with basic DNSBL capability, and plugins for regex rule filtering, bayesian and other tactics - you can also use a really harsh DNSBL if you hate spam more than the risk of tagging "innocent" mail.