On Firefox, we have an online synchronization/backup feature that allows users to sync multiple computers' settings, addons, etc. I've gotten back into using Thunderbird just recently because it is such a powerful program. The only downside that I can see, is that I have spent so much time customizing it and setting up filters and saving my address book, that if my computer crashes or something happens to my profile, it will all be lost. Is there a sync feature with Thunderbird? If not, is there a good program that will backup my entire profile to the web or my external hard drive?