Not sure if that handles v10 - v10?
I think OP's new server is not running SME...
Personally I am a "gradualist" about server migrations - I've been a "one man shop" most of my career and try to find a way to migrate one user or service at a time, adjusting both the old and new servers as each user/service is moved using email forwarding for users and proxypass or DNS updates for services. For anything that cannot be migrated this way I create either a script or detailed notes developed during several test migrations before doing the final migration.
As for things that might need extra attention:
* eMail rules, signatures, and message status
* Fetchmail settings
* File ownership and permissions
* Any SME-based service using cookie-based authentication
* Version issues with apache, php, node, javascript, etc that might require config file changes or application modification
* Encryption and Cipher Suites used by any of https, smtps, imaps, ftps
* upstream connections
* Cloudflare (for example) can be configured to expect a specific certificate from your server -- any upstream system connecting to your SME could have settings that will impact communications with the new server.
* External SMTP relay (if you're using one)
* downstream connections
Servers accessed by the SME server itself may need configuration changes to allow connections from the new system.
* Single Sign-On
Is your SME involved in any sort of SSO?
* daemon users
Apache may be running as "www" or "apache" instead of "httpd", which would impact service control files and file ownership requirements.
* Active directory domain settings?
* Apache, PHP symlink & basedir (generally - any SME default or db-controlled setting that differs from the default on the new server)
* webapp databases & passwords (eg wordpress)
* Server maintenance (I spent a year or more getting comfortable keeping Ubuntu up-to-date before I moved any production services off of SME)
* System security (SME incorporates good overall security settings by default)
* service configurations
* user rights
* firewall rules
* fail2ban
* LetsEncrypt