Before Thunderbird, emails was stored as mbox or maildir format, regardless of what application you used to read it.

Mutt, Pine and KMail all just read those two accepted formats.

Now with Thunderbird, we have to do some type of import which is a conversion.

For years, my mail has been stored in ~/Mail and I would just switch email reading programs from time to time.

With Thunderbird, this is not possible which is why I will be uninstalling the application.

What was nice about the independent storage format was that I could switch from Kmail and Mutt as I wanted for the front end and I could also switch between fetchmail, getmail or even KMail POP3 handling on the backend. Everything was interoperable. Thunderbird is not at this point (yet?).

This ‘independent storage’ is one of the strengths to move to Linux from Windows, you don’t have to deal with many proprietary formats – across applications, certain open formats just work.

My 2 cents on this old thread.