We've got a lot of email in Mozilla on one machine, in several accounts, with subfolders. We upgraded Mozilla, and all the accounts went away. This is, of course, unfortunate.
The data is still there -- we looked at the folders, and there are hundreds of megabytes of files. We immediately copied them to another folder, for extra safekeeping.
So ... how do we tell this version of Mozilla to use those mail files?
(Yeah, we hacked around and have a rather chaotic way which seems to let us read old mail and get new mail, but might not work for the subfolders, and seems somewhat likely to break. So please, if you tell us about how to do stuff, let us know how sure you are about it. We've already got a half-assed answer; we'd like a full-assed one.)
(Yeah, yeah, Back it up early, back it up often. We're more careful with some machines than some others.)