Some related posts from Technorati and Google.

[Drake.org.uk] MessageLabs' 553 error message: Anyway, getting back to the matter in-hand, after some investigative work of my own I found that my web host's (Hostgator - this was several months ago and I now use a different host for this reason alone) SMTP server on the SpamCop RBL. Speaking of SpamCop - has anybody else found them overly aggressive these days - I'm seeing a lot of messages being flagged up as spam by them when I know the sender is innocent.

[Securence.blogs.com] Anti Spam Software & Internet Filters Blog - Securence: Securenceis a leading provider of anti spam software, and Internet filtering servicesthat include email protection and security services for small business,enterprises, educational, and government institutions worldwide. TheCompany’s unique solutions help protect companies and their employeesby scanning email and eliminating threats, such as viruses, worms,malicious content and attachments, and other junk mail before reachingthe end user.

 [Mboffin.com] MBoffin.com - Using Gmail as a Spam Filter: Since I have control over the MX for my domain, I was going to set all incoming mail for my various usernames (in the virtual user and alias tables) to kick over to my GMail account, and then have GMail kick it back to a new account on my mail server whose sole purpose was to receive filtered mail from GMail. By then using client-side or server-side filtering on that account, I can then reject any mail that has not come from GMail, under the assumption that it's coming from a spammer broadcasting to all accounts on my box in hopes of hitting a live account somewhere, because the only legitimate e-mail coming to this new account should have the GMail forward tag on it.

 [Jeremy.zawodny.com] SMTP Sender Authentication, Blog Spam, and PageRank (by Jeremy ...: Privacy: I do not share or publish the email addressesor IP addresses of anyone posting a comment here without consent.However, I do reserve the right to remove comments that are spammy,off-topic, or otherwise unsuitable based on my commentpolicy. In a few cases, I may leave spammy comments but remove anyURLs they contain.

 [Community.bluesecurity.com] The Blue Zone: I've seen some posting in our forums about a potential cause-and-effect relationship between registering an address and receiving more spam. The philosophical concept of causality is notoriously hard to define since every aspect of causation has received substantial debate.

Reflected tags on Technorati: Blog, [Technorati] Tag Results For Pop3, Targeting Spam