From KernelEx Wiki
Thunderbird on Win ME
|Tested release||10.0.12esr and 3.1.20|
|Type||Email Client (POP3, IMAP, & SMTP)|
Thunderbird is a free, open source email application developed by the Mozilla Foundation. It's easy to set up and customize. Latest version official supported on ME/98 is 18.104.22.168 released on 15.March.2010. With KernelEx you are able to install and run Thunderbird up to version 10.0.12esr (Gecko engine 10). Use version 9.0.1, if you have problems with version 10.
Use comp. mode Win 2000SP4.
Version 3.1.20 released on 12.March.2012
Version 10.0.12esr released on 08.January.2013
Choose comp. mode Win 2000SP4 for all versions 3.x.
Thunderbird crashes in order to print. Possibly there will be a workaround.
Version 11 runs, too. This version causes an error in MSVCR80.dll at close.
Version 12 freezes after a short time.
It's possible to install higher versions, but they don't start. Currently there is no workaround.