Postfix not receiving for ONE of many domains after separating web/mail hosting

Without having more specifics for the domains that you are sending/receiving from, we will be limited in what advice we can offer, but I will try and point you in the right direction based on each section of your post.

Since the split and after updating the DNS config, mail will send but not receive for just this one domain. All other domains send/receive as expected.

Are you receiving any error messages? Have your checked your mail logs to see if there are any specific issues that haven't been noticed yet. You should be able to find your Postfix logs in the following directory:

/var/log/mail.log

Zone file looks good. No changes have been made to Postfix/Dovecot configuration.
Thought it might be a DNS config error after the change since the problem seems to be domain-specific.

When you updated your zone files for this domain, did you make sure to update both the MX record and A records? The A record will point to the IP address that the website is hosted on, while the MX record will still point to the Linode IP address.

Are there any redundant records that might be causing an issue?

Have you tried deleting the zone entirely and recreating it?

UPDATE: if I send from any of the mail accounts on my server they will make it to the one troubled mail account. Possible Postfix config issue after splitting web/mail for the one domain?

Unless you manually edited your Postfix configuration, there would not have been any changes when splitting the service.

Our "Guides & Tutorials" page offers a pair of great guides that pertain directly to the the configuration and troubleshooting of Postfix, Dovecot, and MySQL. I would recommend taking a look through both of them to see if you can find any issues with the configuration or setup of your mail service.

Email with Postfix, Dovecot, and MySQL
Troubleshooting Problems with Postfix, Dovecot, and MySQL

Thanks for the reply. I actually opened a support ticket (10678882) and followed any/all troubleshooting steps, etc.

While mail is sent and received properly across all other domains on my slice, this one particular domain can send but not receive. I can send locally via telnet, or from another domain hosted on my slice to the trouble domain. This is what led me to believe it is/was a DNS issue.

There is absolutely nothing being recorded to any mail logs (/var/mail/[dovecot.log|mail.log|mail.err]) when sending from – let's say a Gmail account – to this one particular domain.

Mail does not bounce, and it does not get delivered anywhere, with no reference in the log files at all.

If you peruse the ticket you should see all the pertinent info regarding this. I've checked firewall, ports, used doveadm to confirm accounts are setup properly, etc.

Any other suggestions you could provide would be much appreciated.

RE: deleting the zone file and recreating
I have deleted an re-added some of the records on the zone file, but have not completely deleted and re-added. Will do so now.

Ticket includes postconf and doveconf dumps.

As you stated in your reply above, since nothing has been changed with my postfix or dovecot configs and all other domains work as expected, it seems the problem is elsewhere?

Thanks