How to edit Thunderbird's e-mail preferences

For Thunderbird users, Goebel.net has a nice tutorial on editing your preferences -

Thunderbird can be configured by editing the about:config page, which lists application settings (known as preferences) that are read from the profile files prefs.js and user.js, and from application defaults.

Many of these preferences are not present in the Options or Preferences dialog. Using about:config is one of several methods of modifying preferences and adding other "hidden" ones. In Thunderbird 1.5 or later, about:config is accessed via "Tools -> Options -> Advanced -> General -> Config Editor (button)".

In about:config this option has to be set on true:

mail.server.default.leave_on_server = TRUE

And if you want to save space on the flash drive, it's recommendable to empty the trash bin every time you close the Thunderbird e-mail program:

mail.server.defaul.empty_trash_on_exit = TRUE

The full article can be read here.