Have you set up an email trigger, and you're sure you've followed all the instructions but when you send the email to the right address...nothing happens? Or maybe you see a bounce indicating the message was rejected due to something called a "Relay access denied" error?
The issue is that your SMTP server is configured to allow CNAME expansion for email addresses. With this feature enabled, the email server can sometimes change the "to" address for emails when routing them to their destination.
To use email to trigger a flow in xMatters, you must send an email to an address matching the following format:
But with the CNAME expansion option enabled, an email sent to
might be changed during transit through your email server to something more like
To resolve this issue, you need to work with your IT team to disable the CNAME expansion setting on your SMTP email server.
As an example, here's a description of the CNAME expansion setting on a Sendmail email server (from the Sendmail documentation):
confDONT_EXPAND_CNAMES DontExpandCnames [False] If set, $[ ... $] lookups that do DNS based lookups do not expand CNAME records. This currently violates the published standards, but the IETF seems to be moving toward legalizing this. For example, if "FTP.Foo.ORG" is a CNAME for "Cruft.Foo.ORG", then with this option set a lookup of "FTP" will return "FTP.Foo.ORG"; if clear it returns "Cruft.FOO.ORG". N.B. you may not see any effect until your downstream neighbors stop doing CNAME lookups as well.
xMatters does not use CNAMEs for their mail servers. Instead, mx records go to load balancers, and the request uses the load balancer address instead of the instance hostname which is required to properly source the initiation.
For a more thorough explanation of CNAME expansion, check out these SMTP articles from IETF.org:
(To save you a little time, the money quote appears to be this one: The lookup first attempts to locate an MX record associated with the name. If a CNAME record is found instead, the resulting name is processed as if it were the initial name.)
For more information on using email to integrate with xMatters, see the email trigger description in the online help.