I don't have any of these on a mail server I've run for 20+ years. Mail still works reliably (both send and receive), but all the naysayers are beginning to make me think about converting to GSuite or similar.
If you've ever gotten loads of mailer-daemon bounces for emails that you didn't send, then a spammer has been using your address(es) in the "From" header.
This eliminates that problem.
Big providers like Gmail, Outlook, etc all have a scoring system for sender IP addresses and hostnames. The longer your IP and hostname behaves properly, the more credit it will get.
I imagine starting a new mail server with new ip addresses/hostnames may be more difficult.