[Evolution] Where are label (associations) stored for IMAP?

["James Sleeman" <bitsyboffin gmail com>]

Hi all,  for an IMAP account, when you select to "Label" a message,
where is that Label association stored, is it local, or is it in the
IMAP server.

Reason I ask, is in a coversion from mbox to maildir, my labels have
vanished, and I'm not sure if that is a problem in evolution, or the
maildir conversion.

--
James