WF notifications are blocked

[big]

Hi,
On R12.2.4 DB 11.2.0.4 on AIX

WorkFlow notifications are not sent to recipient. Their MAIL_STATUS=UNAVAIL.

In /var/log/mail file on AIX server I see:

relay=server12.com Host not found.

Is it a problem of sendmail configuration? Or a problem of WorkFlow mailer configuration?

If it's from WorkFlow mailer configuration which parameter should be adjusted?

Or if it is a problem of sendmail configuration what in /etc/sendmai.cf should be added?

Thanks.

[ErmanArslansOracleBlog]

Info:

-WF_DEFAULT- 5 UNAVAIL Auto-Reply:
-WF_DEFAULT- 6 UNAVAIL Auto-reply:
-WF_DEFAULT- 7 UNAVAIL Returned mail:

Are you sure the emails are not sent? I mean are you sure that it is related with outbound? (smtp)
UNAVAIL is usually related with  the imap / inbound side.

Ref Oracle Support: Generally the mail_status is set to UNAVAIL for inbound processing which comes from the notification attributes. When a mail is pending for approval and the person is not available an autoreply mail is sent saying UNAVAIL, hence the mail_status is UNAVAIL.