[oulipo]

Start by simply backing up your emails regularly with BaGoMa

[ableal]

"BaGoMa - A script to Backup Google Mail."

http://sourceforge.net/p/bagoma/home/BaGoMa/

Thanks

[tripzilch]

I was going to suggest GMVault, which I use with success. Anybody got experience to tell me how they compare?

OTOH GMVault does the job fine, which I guess is most important.