VERIFIED SOLUTION i

e-Messaging: Error 'Unknown SMTP Host' using the DNS hostname as the gateway name

Product Feature: Operational Settings
 

Issue

In new installation while setting e-Messaging gateway with hostname  and trying to send emails, error occurred :

User-added image

Configurartion for gateway:
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Emails were send sucessfully if used IP address in configuration. 

Cause

This is not a product issue rather related to host name resolution within that environment.

Resolution

UPDATED: March 30, 2017
Follow these steps:

1. Perform nslookup <host_name> <server_IP_address> 
Substitute the actual host name to be resolve for host_name and the IP address of the DNS server for server_IP_address.
For example, if the host name that to be resolved has a fully qualified domain name (FQDN) of server5.contoso.com and the DNS server's IP address is 111.168.0.200
  • Open Command prompt : type the following command, and then select enter:  nslookup server5 111.168.0.200 
  • Try using the FQDN: nslookup server5.contoso.com 111.168.0.200 
If the host name alone does not resolve,  but the FQDN does, confirm that the primary or connection-specific DNS suffix is configured correctly. 

2. Refer Steps to correct DNS hostname reoslution