==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.1 MARIADB edition.
- Deployed with iRedMail Easy or the downloadable installer?  Downloadable
- Linux/BSD distribution name and version:  CentOS 7
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx):  Nginx
- Manage mail accounts with iRedAdmin-Pro?  Yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Good evening.  I had to swap back to my old email server after creating a brand new one.  I went from 0.9.9 MARIADB edition, to 1.1 MARIADB edition and all databases were updated and correct.  I've been searching all around the forum to find answers but found nothing to help.  Here is the log file message... there are hundreds for each of my clients.

postfix/smtpd[26840]: NOQUEUE: reject: RCPT from mta119b.pmx1.epsl1.com[142.54.244.119]: 450 4.7.1 <this@that.com>: Recipient address rejected: Internal error occurred. Refer to server log for more information.

I can't find the log file that would tell me the exact reason why I'm getting the message.  I got this one from the maillog.  I copied the var/vmail/ directory from the old server using:

sudo rsync -avzp --progress root@<IP address>:/var/vmail/ /var/vmail/

I also updated the SQL database using mysql -u root -p database < database.sql

My certbot certs were checked and good to go, and my DKIM entries were copied over accordingly.  This is the fourth time I've created a brand new server and moved everything over... but it's the first time I've ever lost any incoming emails due to this error.

What can I do to build a new server and trust that it will not reject all of the messages?