GroupWise 12 Primary domain mta shows itself opening and closing every second and it's connection to it's owned post office is closed also.

Note:  This is possible that this issue could affect GroupWise 14 and 18 also.

Answer: Many things were checked on the GroupWise side of things :

1.  Noted the error in the problem GroupWise MTA log showed:

  "I/O error while scanning input queue".

2.  Consider this tid also:  https://support.microfocus.com/kb/doc.php?id=7010474

3.  GroupWise links, 

4.  Possible port conflicts.

5.  Checking for multiple GroupWise MTA's that could be running.

6.  Check for 3rd party programs running on the server that could be accessing the GroupWise domain or post office directory structure.

7.  Rebuilt the domain, renamed GroupWise domain directories in case they were corrupted files or directories.

8.  Does the server have sufficient resources, free disk space and ram memory.  

9.  We also checked for the ability of the server to create and work with open files file, with the /etc/security/limits.conf server configuration file as discussed in tid :  https://support.microfocus.com/kb/doc.php?id=7022238.

What it turn out to be is some type of problem on the OES NSS volume, as when the GroupWise Domain and Post Office were moved to a new NSS Volume the problem went away.