[Spambayes] AVAILABILITY FOR MOZILLA THUNDERBIRD??

[skip at pobox.com]

    Kevin> ThunderBayes is an add-on for Thunderbird that provides very nice
    Kevin> integration between Thunderbird and SpamBayes. SpamBayes status
    Kevin> for each message can be shown in a message list column, and
    Kevin> messages may be trained as spam/ham with a convenient toolbar
    Kevin> button.

How does it integrate?  It looks like the only download is an xpi file.
Isn't that a little extension for Thunderbird?  Does it include SpamBayes?

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