We have an odd email setup.  Our primary, internal
mailserver is an old Solaris 9 system running postfix,
imap and pop.  This system is really getting bogged
down and we plan to move mail to another system soon.
But short term we have started running imap and pop
services via xinetd on two SL304 systems to offload
the main mail server AMAP.  All three servers mount
the mail directory from the same filer (NetApp) via
NFS.

For most users, changing the imap or pop server in
the client just works (as it should).  But a handful
of users, most running Thunderbird on Linux (a couple
running default clients on Mac or XP laptops) have
found that when they switch servers, they see an
empty inbox, or only a handful of the most recent
emails there, no matter how many times they try to
sync.  If they switch back to the slow, original
server, everything shows up again.

The desktops are running 4.4 and some version
of Thunderbird 1.5 or 2.0.

Have any of you seen anything like this?  Is it an
imap (and pop) problem on EL3, or a protocol bug,
or what?  I don't see it as a thunderbird issue
since we have a handful of Mac and Windows users
seeing it on clients that came with their MacOS
or XP.  Of course, weirder things than that have
happened...

Thanks,
Miles