Mailserver MAILENABLE Security Enhancement

I'm seeking an expert of mailserver logic to enhance the security of my mailserver.
Focus on comprehensive protection against potential threats.

Mailserver is MailEnable v.10.48 Standard Edition.
Server is Windows 2019, access allowed via AnyDesk (or Teamviewer) only
Everything works perfectly. SPF and DKIM implemented.

Ideal Skills:
- Extensive experience in mailserver security
- Proficiency in setting up robust security measures
- Ability to identify and mitigate potential vulnerabilities
- Knowledge of the latest security trends and threats

I need to implement external tools (possibly free, preferably “portable”) to improve security
- implement IPBAN [Free software to block out attackers quickly and easily on Linux and Windows]
- implement a script to free certificates renew (using WACS = LetsEncrypt)
- antivirus (such as ClamAV)
- DR rules and procedures