I can confirm that warning messages appear in the log by uw-imapd. Normally I do not offer POP3 to my users, just IMAPs and with that I never had any issue. Now for testing I activated POP3 locally in addition and telneted to it. In result I get the message too:
==> /var/log/imaplog <=Jun 28 19:06:12 blacky ipop3d[14128]: Trying to get mailbox lock from process 29363 Jun 28 19:06:13 blacky ipop3d[14128]: Mailbox vulnerable - directory /var/spool/mail must have 1777 protection Jun 28 19:06:13 blacky ipop3d[14128]: Login user=adalloz host=localhost.localdomain [127.0.0.1] nmsgs=207/207 Jun 28 19:06:27 blacky ipop3d[14128]: Mailbox vulnerable - directory /var/spool/mail must have 1777 protection Jun 28 19:06:27 blacky ipop3d[14128]: Logout user=adalloz host=localhost.localdomain [127.0.0.1] nmsgs=207 ndele=0
So I suggest checking bugzilla for reports about that. If nothing is in there you might fill in a report yourself. Though I doubt there will be ever a fix as uw-imapd is no more shipped with current FC2. You may switch over to dovecot or disable POP3 and let your users use IMAP. Or
I do use uw-imapd. What is shipped with fc2? how to switch over to dovecot in fc1? Any document or link I can read? Thanks!
Hongwei