It means the DNS resolver the zimbra server is using is not aware of the MX record you've set up.

You might want to check the SplitDNS wiki page.

The MX should be (ie: it has to be) a FQDN.

So you have two mistakes here.
The first is you're using an IP address instead of a FQDN.
The second is you've added a dot at the end of the IP address (this is only to be used with FQDN).

First of all, you should upgrade your server, because you're at risk. https://forums.zimbra.org/viewtopic.php?f=15&t=65932 Then, about the auth and LDAP, the best way (ie: cleanest and most easy to deal with on long term) is to have an external LDAP server used by all your apps to authenticate a...

mateusscheper wrote:8.7.11_GA_1854.FOSS.

You should be running 8.7.11_GA_3800 (that's Patch P11).

Your server might be compromised, you should check the thread above.

Which version of ZCS are your running?

viewtopic.php?f=15&t=65932

Rolling upgrade works from 8.6 to 8.7.
Also to 8.8.

There are bugs in some specific setup.
For example if you try to enable 2FA before the end of the upgrade: https://bugzilla.zimbra.com/show_bug.cgi?id=105056

You're not alone. There were so many issues with 8.7 and 8.8 that we chose not to upgrade (till things are settled, we were thinking about this summer). 8.6 lacks features (NG modules) but at least it's rock-stable. It's nice Zimbra/Synacor provided these security patch for 8.6. It also shows they a...

You're stuck. The last patches for 8.6.0 broke the signatures (P13 and P14). To be more precise, they broke the "pictures in signature" feature (when you add an inline image to the signature, it's silently stored in the briefcase then anonymously shared). Zimbra/Synacor support is very awa...

Your server might be compromised.
It's not patched against the last XXE, you should look at the sticky thread about it in this sub-forum.

This was already the case in 8.7 IIRC.

Go through this thread, Frédéric released a script (and listed the bug related to the issue in last august).
http://lists.zetalliance.org/pipermail/ ... 01259.html