AFAICT the configuration on this computer is the same as that on
another where postfix works just fine. Obviously, something is different.
The report of a mystery error is not much help.
I cannot determine the failure. Postfix finds the authentication data,
and promptly fails authentication.
What has this gone wrong?
Below are the log entries for one failure, and an excerpt from <main.cf>.
----[ log entry ]----
(see attached file)
----[ end ]----
> 2019-03-27T14:16:57-0700 sma-station14l postfix/smtp: warning: SASL authentication failure: GSSAPI Error: Unspecified GSS failure. Minor code may provide more information (No Kerberos credentials available (default cache: DIR:/run/user/51/krb5cc))
despite lack of GSSAPI credentials, and fails.
> 2019-03-27T14:16:57-0700 sma-station14l postfix/smtp: connect to subsystem private/defer