I dl TB 2 . Since then, I keep receiving the attached error every time I try to send an email
my pc is running a winxp pro sp2 & I use a 256Kb dsl connection
The SBL is a realtime database of IP addresses of verified spam sources and spam operations (including spammers, spam gangs and spam support services), maintained by the Spamhaus Project team and supplied as a free service to help email administrators better manage incoming email streams.
The SBL is queriable in realtime by mail systems thoughout the Internet, allowing email administrators to identify, tag or block incoming connections from IP addresses which Spamhaus deems to be involved in the sending or origination of Unsolicited Bulk Email (aka "Spam").
The SBL database is maintained by a dedicated international Spamhaus team based in 9 countries, working 24 hours a day, 7 days a week to list new confirmed spam issues and - just as importantly - to delist resolved issues.
The Spamhaus Exploits Block List (XBL) is a realtime database of IP addresses of illegal 3rd party exploits, including open proxies (HTTP, socks, AnalogX, wingate, etc), worms/viruses with built-in spam engines, and other types of trojan-horse exploits.
The error message indicates that the recipient of your e-mail has blocked the IP address of your mail server because it has been listed as a sender of spam. You may need to contact your ISP or whoever is hosting your e-mail server about this to see if they can get delisted from Spamhaus.
I have Spam Haus plugged into my Exchange server. I used to get over 1k spam messages per day for a 4 user account mail server until I switched to Exchange. Now I don't see any spam. Most of the protection is due to the excellent spam filter built into Exchange, Intelligent Message Filter.
That error is being returned by the mail server you're trying to use, which is kind of nasty -- ISPs generally shouldn't block their own customers.
Make sure Thunderbird is configured to use your ISP's SMTP server and not some third-party one, and then if it still doesn't work call your ISP. They screwed up and forgot to exempt their customers from blacklisting.
I experienced this once before. The company I was using as a web host also had other sites on the same server. Some of those sites were spamming, causing a block on the server. Needless to say you can't control who your neighbors are, so the we had to be moved to another server. That resolved the problem.