Whenever the delivery status of a mail message changes, sendmail logs the event and includes the stat= to specify why the change happened. For example, a mail message might initially be queued because the recipient's host was down:

stat=queued

Later it might change again because it succeeded in being delivered:

stat=Sent (HAA03001 Message accepted for delivery)

In transmitting a mail message via SMTP the stat= will include the actual text that the other host printed when it accepted the mail message, as shown earlier. But in delivering locally, the stat= is more succinct:

stat=Sent

In the case of bounced mail the stat= will show the reason for failure:

stat=User unknown

The stat= syslog equate is included only in recipient records.