Thunderbird Message Filter Import/Export is a thunderbird/mozilla extension to import/export message filters. You can to Support Thunderbird Filter Import/Export.
You may also want to try our another Firefox Add-on AutoPager.
AutoPager is a Firefox extension which automatically loads the next page of a site inline when you reach the end of the current page for infinite scrolling of content.
By default AutoPager works with a ton of sites, including Lifehacker, the New York Times, Digg, and, of course, Google.
The problem is that Customized headers are not ported, so the following will happen: I am filtering on a custom header to trap spam in Windows, and when I port to the Mac, the filter does come across successfully, but without any knowledge of the custom header, and instead the first header - Subject - is inserted in its place. This, not suprisingly, plays havoc with the filtering, but *there isn't any warning* and one could lose lots of mail before realizing what is going on...especially when the spam folder deletes after 1 day (say).
You can now update to 
