Mailbox Formats

[Jonathan Hutchins]

I'm betting that somebody here uses multiple mail clients.  I've been 
wondering which ones use compatible mailbox formats.  For instance, KMail 
seems to store it's mail in a database format of some sort.  Pine moves stuff 
from the mail spool to the user's tree when it opens.  Mail actually reads 
the mail spool, I think.

The reason for asking is that I have a lot of archival mail in KMail, and I'm 
not sure how to go about making it portable.  If I were using a more common 
mailbox format, it might be easier.