Thunderbird is an okay email application, but their method of saving and restoring profile data --- ie, emails, address book , settings -- stuff that you could not possibly want to save securely -- is the absolute pits.
And you can't automated, either. Oh, I'm sure you could write a script to do it, or even buy one, but the product itself? Heh. Suck it up. Their theory seems to be If it was hard to code the product, it should be hard to use the product.
Not that they're alone in that opinion.