Update your Thunderbird (Firefox) manually
This is modified from a post send by leepa
Manual update of Firefox (Thunderbird):
0. Close Firefox (Thunderbird) Portable
1. Create a subfolder firefox-update (thunderbird-update) in a folder where application is installed
2. Download appropriate .mar file (from any ftp mirror under e.g. /pub/mozilla/thunderbird/1.5.0.8/update/win32/en-US7)
3. Copy the updater.exe file from application folder to firefox-update (thunderbird-update) subfolder
3a. Also copy updater.ini from application folder to firefox-update (thunderbird-update) subfolder
4. Copy the mar file to the folder created in step 1 and change its name to update.mar