Thunderbird (bis)

So the answer to my question is : there is no fu**ing way to choose which columns you want to display in the mailboxes, it's apparently a default of "sender" OR "sendee" (or whatever it's called in English) depending on whether Thunderbird decides that it's a "in" or an "out" folder.

And the import from Outlook obviously isn't TOO good at determining whether a folder is in or out.

#&@*$[£§!?!

Not to mention that for some reason, the out messages from one of my addresses go to the in sub-folder dedicated to it, not to the "sent" one...