Thunderbird exports and Fedora Upgrading

[TroyGeek]

Hello,
Usually when a new release of Fedora comes out I like to backup my data, 
format the hard drive, and then then install a fresh release instead of 
'upgrading' since it seems cleaner.

I use Mozilla Thunderbird for my email. I don't see any export options 
to save my emails. I'm wondering how I can backup/export my email from 
Thunderbird so that I can be prepared for when FC3 comes out and I 
upgrade. I want to be able to keep all my email.

Any ideas? Just copy a directory or something?

thank you!

~ TroyGeek ~