Once I've obtained free certificates from Let's Encrypt, preferrably with dehydrated on FreeBSD, I'm going to modify Postfix's config file so they can be used to secure SMTP traffic.
Once I've obtained free certificates from Let's Encrypt, preferrably with dehydrated on FreeBSD, I'm going to modify Dovecot's config file so they can be used to secure POP and IMAP traffic.
Once I've obtained free SSL certificates from Let's Encrypt, preferrably wildcard ones, as described in another article here at Mimar - Let's Encrypt Wildcard Certificates On FreeBSD With BIND DNS Validation - I'm going to combine them into single PFX file so it can be used by Microsoft Exchange to secure IMAP, SMTP, POP and IIS services.