550 5.7.1 Relaying Denied

This is one of the most common errors after setting up your mail server.   All mail servers deny relaying by default due to the worldwide problem of spams.  In Oracle Apps if you see this error in your workflow mailer notification logs or in /var/log/syslog, you should check for these:

The Workflow mailer works in this way:

A connection is made from application tier server to the mail server on port 25 (SMTP)

When the smtp server gets the mail from application server, it first checks whether the application server's IP exists in /etc/hosts of the sendmail server.  In our environments, we usually configure the concurrent tier as the mail server by starting the sendmail server on it.

Unless and until you have the entries for your application web servers in /etc/hosts, sendmail will not accept the mail for relay to any destination except its own domain.

For example, if I connect to port 25 and send a mail to a different domain

telnet vip.justanexample.com 25

Trying 192.168.1.17...

Connected to dbtier.justanexample.com

Escape character is '^]'.

220 physicalserver.justanexample.com ESMTP Sendmail 8.13.8+Sun/8.13.8; Sat, 15 Nov 2008 10:33:45 -0500 (EST)

MAIL FROM: john.doe@justanexample.com

250 2.1.0 john.doe@justanexample.com... Sender ok

RCPT TO: jane.doe@someotherdomain.com

550 5.7.1 jane.doe@someotherdomain.com... Relaying denied

However if the @ in the mail is the mail server name then relaying is ok.

RCPT TO: mailuser@vip.justanexample.com

250 2.1.5 mailuser@vip.justanexample.com... Recipient ok

The rule is 

1. Mail will be accepted from all IPs as long as the server name after the @ in email address is the mail server or the hostnames present in /etc/mail/local-host-names.  For our example, make sure that you have the logical and physical hostnames of all application servers and the DB cluster name in /etc/mail/local-host-names.

2. Mail will be accepted for relay from those IPs whose IP and hostnames are correctly mentioned in /etc/hosts file of the mail server in this format:

IP address   servername.domainname   servername

192.168.1.17    vip.justanexample.com    vip

If you take care of these two things, you'll not see the 550 5.7.1 Relaying denied message in Oracle Apps 11i.