Excellent Tool Rated 4 out of 5 stars
I had some trouble installing this, and it took me a while to find the Options page under Addins to configure where the files go when you manually designate spam or ham. The author's website has basic instructions, but more specific would be nice for those of us not as technically versed. But once I got it the extension worked orders of magnitude better than the built-in junk filter after training only about 20 emails. I did have to manually adjust the SpamBayes configuration for multiple POP3 accounts (see the message from Head Geek in the discussions) after I set the account settings options within Thunderbird. Great tool -- even better with better instructions and if the multiple accounts configuration issue could be addressed.