The EEE PC is a very unobtrusive device, but it also has its odd qualities: The screen is often too small for configuration purposes on the built in Xandros Linux. In many cases you cannot reach the OK button at the end of a configuration window and often configuration options are left outside the usable screen.
That almost drove me crazy when I configured the Thunderbird e-mail program. The "Leave Mail on Server" option was unreachable outside the screen and there is no possibility to change the default resolution on the Asus EEE PC. Since the EEE PC has only few Gigabyte of storage it's not exactly the device where you want to download all your e-mails.
But fortunately I found a workaround: Thunderbird can be configured by editing the about:config page. That's a powerful feature of Mozilla applications 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
That's all. Have fun with the Asus EEE PC! It's the perfect mobile device for quickly answering e-mails, because it has a full QWERTY keyboard and boots up in 30 seconds.