[Dovecot] dovecot help

[Andy Fadich]

Hello,
 
I have a mail server which I upgraded yesterday.  
 
OLD:
Redhat 9
sendmail (very old version)
UW ipop3d
usermin with readmail module for webmail access (very old version)
 
NEW:
Fedora Core 6
sendmail 8.13.8
Usermin for webmail again
dovecot 1.0.0

# /etc/dovecot.conf
protocols: pop3
login_dir: /var/run/dovecot/login
login_executable: /usr/libexec/dovecot/pop3-login
mail_location: mbox:/home/%u/mail:INBOX=/var/spool/mail/%u
mail_executable: /usr/libexec/dovecot/pop3
mail_plugin_dir: /usr/lib/dovecot/pop3
pop3_uidl_format: %08Xv%08Xu
auth default:
  passdb:
    driver: pam
  userdb:
    driver: passwd

 
Everything is working great, besides a few glitches here and there. However,
When accessing mailboxes via webmail (usermin) an email shows up with a
subject of DON'T DELETE THIS MESSAGE -- FOLDER INTERNAL DATA. As far as I
can tell, this is an IMAP folder directory portion of the mailbox file that
should be hidden.  
 
We don't use IMAP at all, and it is confusing people when they see this
message that never was in their webmail before.

Anyone know how to hide, remove or otherwise fix?
 
Thank you in advance.
 
Andy