--------- /etc/exim4/exim4.conf WITH authentication ---------
...
remote_smtp_smarthost:
  debug_print = "T: remote_smtp_smarthost for $local_part@$domain"
  driver = smtp
  hosts_try_auth = ${if exists {CONFDIR/passwd.client}{DCsmarthost}{}}
# add the following line 
  port = 587
  tls_tempfail_tryclear = false
...
 --------------- /etc/exim4/passwd.client ---------------
# password file used when the local exim is authenticating to a remote
# host as a client.
#
# see exim4_passwd_client(5) for more documentation
#
# Example:
### target.mail.server.example:login:password
mail.ncf.ca:ag221:MYPASSWORD