unable to look up host hotmail.com: Name or service not known

[cce]

Hello. I have a Zimbra Mail Server 8.6 on Centos 7 and Bind9. It worked correctly, from one day to the next it stopped sending emails to any external domain, it only sends to accounts of the domain itself. This is the error that comes out:

nano /var/log/zimbra.log

in English:
Jul 5 12:18:30 mail postfix/smtp[2749]: AD9AD166117B: to=<cuenta@gmail.com>, relay=none, delay=20, delays=0.03/0/20/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name service error for name=gmail.com type=MX: Host not found, try again)


In the body of the email that bounced me it says this:

Undelivered....

<cuenta@yahoo.com.ar>: unable to look up host yahoo.com.ar: Name or service
not known

Any ideas? I need help, Thank you.-

[phoenix]

<cuenta@yahoo.com.ar>: unable to look up host yahoo.com.ar: Name or service
not known-

That would indicate a DNS problem to me, have you run any dig commands to see if the domains can be resolved from your zimbra server?

BTW, you're on an old version of ZCS. I'd suggest you get yourself on the latest release of ZCS ASAP.