I guess this is the same type of question like
[SOLVED] Spam training on multiple frontend Zimbra MTAs. If anybody will come up with specific details and spend time studying, why it should or should not be there, nobody will even drop a note for helping a little bit (zimbra people

?). As far as I understand in Zimbra (especially multiserver installation), each small detail in logs can indicate potential problem, but there are vast amount of info, which in most cases do not say anything. The challenge for us, managing zimbra, is notice something, and "leave it until after something gets in trouble".

And then, by spending hours, we can come up with solution, about which you were aware half year ago, to understand, that then it became a problem.
Nevertheless, main issue on Zimbra proxy was solved due to network settings. And I'd say - without running CLI scripts on Mailbox server at all - only Proxy. Although, have to say, that whether it was a problem of connection, or not fully functional setup script, but even with connection to LDAP, new server installs asked for manual correction in zmlocalconfig settings and Proxy / Mailbox port tunings.