Unity Connection 9.1 SMTP domain

[Steven Luton]

Can the SMTP domain be different than the OS domain?  Obviously we are running into the same issue as everyone else regarding SMTP domain being the same as the exchange environment.  If I just make the SMTP domain differnet than the OS domain, will that break anything?  I have three clusters built all on the same domain, company.net.  Their SMTP domains are hostname.company.net.  The company does not want to have to build three different domains just for the three unity connection clusters, which, according to Unity Connection Networking Guide, all the clusters need to be on a unique SMTP domain for Intersite or Intrasite linking to work correctly.

Any help on this is appreciated.  Cisco TAC seems to be clueless.

[Jonathan Schulenberg]

Yes it can be different than the OS domain. Secretly CXN is a Postfix mail server so this is essentially configuring the domain of the subscribers' mailboxes. As it will warn you though there are several service-impacting daemons that MUST be restarted after making the change.

As you mentioned, the networking guide does require unique SMTP domains per-cluster. This is because most of the inter-cluster traffic occures over SMTP, including message delivery. I typically recommend a semi-human friendly nomenclature such as:

na.voicemail.domain.com

emea.voicemail.domain.com

apac.voicemail.domain.com

Please remember to rate helpful responses and identify helpful or correct answers.

[Steven Luton]

In our setup we have three clusters with SMTP domains:

CAM-UCXN-1.domain.net

USWST-UCXN-1.domain.net

TOK-UCXN-1.domain.net

The domain.net are the same on all the clusters.  The domain.net is also the same as the exchange environment.  Our SMTP domains are already different from each other so interclustering should work just fine but becaust the domain.net is the same as our exchange evironment we may have issues with replying back to voicemails internally.  So if I just change the SMTP domains to .com at the end, we should be good in all areas, right?

Thank you for your response by the way.

[Jonathan Schulenberg]

The SMTP Smarthost defined in CXN must be configured to route mail for whatever FQDN you decide toward the respective CXN cluster. The process depends on the Exchange version but it's a Hub Transport-related SMTP Connector. Exchange also must accept unauthenticated SMTP relay from the CXN server IP addresses. As long as this is setup properly replies to messages (even without VMO installed) should work correctly.

For example: If CAM-UCXN-1.domain.net needs to send a message to TOK-UCXN-1.domain.net it sends the message to the SMTP Smarthost which is expected to relay it to TOK-UCXN-1.

Please remember to rate helpful responses and identify helpful or correct answers.