mailserver/imap/10-auth.conf

disable_plaintext_auth = yes

auth_mechanisms = plain login

passdb {
  driver = sql
  args = /etc/dovecot/sql.conf.ext
}
userdb {
  driver = static
  args = uid=vmail gid=vmail mail_home=/home/vmail/%d/%n mail_location=mbox:~/mail:INBOX=/home/vmail/%u
}