[Dovecot] Dovecot rejecting Vpopmail User 89

[hobie at rumormillnews.com]

I'm working to get Dovecot 2.0.13 working along with qmail, Vpopmail and
Squirrelmail on a Debian 6.0.2 system, Dovecot compiled, not from a
package.

Vpopmail has a widely known assigned user/group ID of 89 and is the owner
of all the mail folders.

Regardless of value of first_valid_uid (1, 89, other), Dovecot denies
Squirrelmail connection, saying it can't allow access to UID 89. "Couldn't
drop privileges", it says. I'd be grateful for fixes, suggestions, or a
pointer to an existing answer to this problem.  Thanks ahead. :)

Presently dovecot -n shows:

# 2.0.13: /usr/local/etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-5-amd64 x86_64 Debian 6.0.2 ext3
auth_debug = yes
disable_plaintext_auth = no
mail_debug = yes
mail_location = maildir:/home/vpopmail/domains/%d/%n/Maildir
maildir_very_dirty_syncs = yes
passdb {
  driver = vpopmail
}
protocols = imap pop3
ssl_cert = </etc/ssl/certs/dovecot.pem
ssl_key = </etc/ssl/private/dovecot.pem
userdb {
  driver = passwd
}
userdb {
  args = quota_template=quota_rule=*:backend=%q
  driver = vpopmail
}

--hobie