SMTP is used in relay mode.
I changed my wife's e-mail (outlook on a MAC) in preparation for her overseas trip so she is using port 993 for outgoing mail to get away from port 25 being blocked.
One UTM went very well, no problems, second (main UTM) continual failures because of authentication. Strange should automatically bypass the outgoing smtp proxy which is not setup to handle secure mail and use the PF rule.
Would appear I am wrong, when I turned smtp off the errors stopped.
Nothing in the smtp log that looks like an error to me.
Ian