Although we automatically back up e-mail, that backup is only used in emergencies such as major hardware failures. So we've put together this tutorial on how to back up your e-mail yourself, in case your own computer crashes or is lost.
Outlook Express
To back up mail files in Outlook Express, look for the following directories on your system:
C:\Documents and Settings\User Name\Application Data\Identities\
C:\Documents and Settings\User Name\Application Data\Microsoft\Outlook Express\
C:\Documents and Settings\All Users\Application Data\Microsoft\Outlook Express\
The address book is normally located in the following directory:
C:\Documents and Settings\User Name\Application Data\Microsoft\Address Book\
You can simply copy these folders and keep them in a secure place.
Mozilla Thunderbird
Mozilla Thunderbird saves all your e-mail, address book, bookmarks and more in the “Profile” folder, which on Windows is located here:
C:\Documents and Settings\User Name\Application Data\Thunderbird\Profiles\
Alternatively, you can use a free program such as MozBackup, which easily backs up (and restores) your e-mail, address book, Firefox bookmarks and much more.
Apple Mail
For Apple Mail you can use a free program, Email Backup 2.0, which can back up both Apple Mail and Thunderbird for OS X. Alternatively, you can copy the files in:
~/Library/Mail
That is the “Mail” folder inside the Library folder within your own user folder.
Storing your backups
It's better to keep the copies somewhere other than your own computer. For example, you can burn them to a CD/DVD or transfer them to a USB thumb drive. If you worry about the security of your backups, you can encrypt them with TrueCrypt, a free program for encrypting files.