Linux - /etc/mail/sendmail.cf is changed and mails are not received.

ISSUE:

We had issues in send mail from Linux for Oracle centralized Alert.

Cause:

Exchage server setting was changed.

Diag:

Check the /etc/mail/sendmail.cf for relay server IP.

Try to ping and telnet the port.

ping excl-prod-01 ==> it worked
telnet excl-prod-01 25 ==> it failed

telnet: Unable to connect to remote host: Connection refused

Solution:

Check with windows team for correct exchange server host name,IP and check the DNS server for host name IP address is set correctly.

Then updated /etc/mail/sendmail.cf line below with new exchange relay server.

"# "Smart" relay host (may be null)"

then restarted 

#/etc/init.d/sendmail stop

#/etc/init.d/sendmail start