Disabling DNS Lookup Zimbra 8.8.15

[mdamda]

Hi All,

We are upgrading to Zimbra 8.8.15 Open Source from an old Zimbra 8.0.4 install for an internal LAN based email system that is intentionally disallowed to communicate with the outside world / email.

Hence, we were running everything with private IP addresses only within a single private domain.

We have already simulated an upgrade to 8.6.0 as part of the recommended upgrade path, but 8.8.15 seems to omit the option to uncheck/disable "Enable DNS lookups", (present in 8.0.4 and 8.6.0, but not in 8.8.15) which seems to prevent our emails from sending out properly. I can confirm that the checkbox still exists in 8.6.0, and as of that patch level, we are still able to send and receive emails normally.

Has this option moved somewhere else? How would we get our setup running again with 8.8.15?
(There is a new option in that same spot in 8.8.15 - a dropdown box with label: SMTP DNS, with 3 options, Enabled, Disabled and DNSSEC, but all 3 settings still prevents the sending out of emails).

Thank you!

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[BradC]

When you say "all 3 settings still prevents the sending out of emails", have you looked through the various logs to see what errors are coming up?

If the system can't see the world, where is it sending mail to? To rephrase that, what would the Zimbra SMTP server be trying to connect to?

[mdamda]

Hi, and thanks for the reply.

I'll check the log and get back.

The email server is to be used strictly on LAN, which is to say, a private domain only accessible by people on our LAN which isn't even registered.

All emails are only sent to other people within the organization / LAN and the zimbra server should not need to resolve any other domain except itself (but it is on a private domain) since the way we set up this up is that we should only be able to email people inside the organization.

Hope this explanation is sufficiently clear (not very well versed with these terms).

Reading up a bit about this, I believe I may now need to set up split dns / bind?

Thank you!

[phoenix]

Reading up a bit about this, I believe I may now need to set up split dns / bind?

That's correct and a DNS server is always needed for a ZCS server as that's how mail gets delivered, if you're behind a NAT device then you will need a DNS server on your LAN (Split DNS as you've mentioned). This topic has been covered many times in the forums and even in the Zimbra Documentation.

[pkhairnar]

You may refer wiki links: https://wiki.zimbra.com/wiki/Split_DNS
https://blog.zimbra.com/2023/02/setting ... ng-zimbra/