[Dovecot] sasl authentication via dovecot

[Frank Church]

I am setting up a Postfix/Dovecot/Virtual Domains system, with virtual
tables using Postfixadmin and MySQL. Incoming mail is accepted for the
virtual mailboxes, but when I try to retrieve mail from Outlook or
Thunderbird I get errors

You cannot log in to abc.server.net because the server has disabled
login. You may need to connect via SSL or TLS. Please check the
account settings for your mail server

As Dovecot is handling the auth I suspect that it is where the problem
lies. Are they any faults in the settings below that could be the
cause?
As I understand it because Dovecot is handling the login and
monitoring the IMAP and POP ports. All the initial authentication is
supposed to be handled there before Postfix gets involved.
Running lsof -i:port  on ports 110, 143, 993 and 995 shows that
dovecot is handling all those inbound connections.

I am also seeing messages in the log as follows
dovecot: imap-login: Aborted login: rip:81.150.x.x, lip=66.90.x.x

my auth section in Dovecot is as follows

auth default {
  mechanisms = plain login
  passdb sql {
    args = /etc/dovecot/sql.conf
  }
  userdb sql {
    args = /etc/dovecot/sql.conf
  }
  userdb prefetch {
  }
  user = nobody
  socket listen {
    master {
#      path = /var/run/dovecot/auth-master
      path = /usr/local/var/run/dovecot/auth-master
      mode = 0660
      user = vmail
      group = mail
    }
    client {
      path = /var/spool/postfix/private/auth
      mode = 0660
      user = postfix
      group = mail
    }
  }
}
 My sql.conf is as follows

driver = mysql
connect = host=localhost dbname=postfix user=dovecot password=password
user_query = SELECT concat('/var/vmail/', maildir) as home,
concat('maildir:/var/vmail/', maildir) as mail, 601 AS uid, 12 AS gid,
concat('dirsize:storage=', quota) AS quota FROM mailbox WHERE username
= '%u' AND active = '1'

password_query = SELECT username as user, password,
concat('/var/vmail/', maildir) as userdb_home,
concat('maildir:/var/vmail/', maildir) as userdb_mail, 601 as
userdb_uid, 12 as userdb_gid FROM mailbox WHERE username = '%u' AND
active = '1'


this is the smtpd section from main.cn
# ---------------------- SASL PART START ----------------------
smtpd_sasl_type                 = dovecot
smtpd_sasl_path                 = private/auth
smtpd_sasl_auth_enable          = yes
#smtpd_sasl_local_domain        = $myhostname
smtpd_sasl_exceptions_networks  = $mynetworks
smtpd_sasl_security_options     = noanonymous
broken_sasl_auth_clients        = yes
# ---------------------- SASL PART END ----------------------