Perhaps they are but I prefer to see some confirmation that they are correct. You should provide the output from all the commands in the 'Verify....' section of the
Split DNS article.
I mean another MTA running on your Zimbra server, CentOS by default install and enables postfix, you need to check if it's running and if it is disable it and stop the current one from running.]
That would be because the MTA isn't running, go to a terminal on your Zimbra server and run the following:
Code:
su - zimbra
zmcontrol status