Maildir support has been considered beta for a long time in Thunderbird, and using it for anything ‘critical’ doesn’t sound possible unless you like to live dangerously (for me, everything to do with email is critical- some messages are more important than others, but I really can’t deal with email being unstable, it’d be like the postal system being consistently unstable). Do you use the maildir format with Thunderbird? - if you have, how do you find it?