I've published a great deal of information about Firefox and tons of extensions that have been developed for it but I've never done the same for Thunderbird, the email client that is developed by Mozilla.
I started using Thunderbird about a week ago when I imported all my emails from Opera to it and I like the email client a lot. It is fast, I can sort all emails the way I like it and the spam mail filter is awesome even without third party tools.
The list of extensions disappointed me a little bit, 297 add-ons is not much considering that Firefox has 1863 add-ons listed. I nevertheless compiled a list of the ten most useful Thunderbird add-ons according to my opinion, yours may and probably will differ on the subject.
Update: We have removed all extensions that are not compatible with the most recent versions of the Thunderbird email client.
Five more, good ones but specialized:
Two not so serious ones:
While all extensions are still available for download for the email client, it needs to be noted that some may not work anymore in the latest version of it.
Update: Time has passed, and lots of useful extensions have been created for the Thunderbird email client in that time. Here is a list of new extensions that you may want to consider.
Ghacks is a technology news blog that was founded in 2005 by Martin Brinkmann. It has since then become one of the most popular tech news sites on the Internet with five authors and regular contributions from freelance writers.