[Dovecot] Couldn't drop privileges

[LuKreme]

attempts to login result in:

dovecot: imap-login: Login: user=<lists@*munged*>, method=PLAIN, rip=ip.xx.yy.zz, lip=75.148.117.91, mpid=75104, TLS, session=<cBjCqf/jdwAXGJaN>
dovecot: imap(lists@*munged*): Error: user lists@*munged*: Couldn't drop privileges: User is missing UID (see mail_uid setting)
dovecot: imap(lists@*munged*): Error: Internal error occurred. Refer to server log for more information.

Local (shell) user authentication works fine. It looks to me like the authentication is working based on the first line, so I don't think the issue is in the dovecot-sql.conf.ext

$ cat dovecot-sql.conf.ext
driver =  mysql
connect = host=localhost dbname=postfix user=dovecot password=dovecot
default_pass_scheme = MD5-CRYPT
password_query = select password from mailbox where username ='%u'
user_query = select maildir from mailbox where username = '%u'

# home is set in userdb static, kept for history
#user_query = select concat('/usr/local/virtual/', maildir) from mailbox where username = '%u'
#user_query = select concat('/usr/local/virtual/', maildir), 'vpopmail' as uid, 'postfix' as gid, from mailbox where username = '%u'

#iterate_query = SELECT username AS user FROM users


# 2.2.5: /usr/local/etc/dovecot/dovecot.conf
# OS: FreeBSD 9.1-RELEASE i386  
auth_mechanisms = plain login
disable_plaintext_auth = no
mail_location = maildir:~/Maildir
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date ihave
namespace inbox {
  inbox = yes
  location = 
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    auto = subscribe
    special_use = \Junk
  }
  mailbox NotJunk {
    auto = subscribe
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix = 
}
passdb {
  driver = pam
}
passdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
ssl_cert = </etc/ssl/certs/dovecot.pem
ssl_key = </etc/ssl/private/dovecot.pem
userdb {
  driver = passwd
}
userdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
userdb {
  args = uid=vpopmail gid=postfix home=/usr/local/virtual/%u
  driver = static
}

I have also tried:

userdb {
  args = uid=vpopmail gid=postfix
  driver = static
}

sql users all have their mail in

/usr/local/virtual/lists@*munged*

$ ls -lsd /usr/local/virtual/lists\@*munged* 
8 drwxr-xr-x  12 vpopmail  postfix  512 Aug 14 21:40 /usr/local/virtual/lists\@*munged*

[New thread because the old one's original issue is solved]

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