help trouble shoot mail server on my local mac

Apparently the mail server that my now-ex-significant-other (ESO) installed on my MacBook Pro 13" has stopped working. I was hesitant to use iCloud and my notes were getting messed up syncing between my Mac, iPhone, and iPad. The ESO installed a mail server on my local machine so whenever the 3 devices were on the same network the notes would sync. Worked flawlessly until a few days ago when a certificate is expired message popped up while using my iPad and I was able to say ignore it and it worked. However, today, my Mac Mail is saying the server is offline and I can't make the account go online.

This is what I know:

Mail says "The server returned the error: Mail was unable to connect to server “marlinespikes-macbook-pro.local” using SSL on port 993. Verify that this server supports SSL and that your account settings are correct."

And in my home directory is a folder called Maildir that the ESO said never touch. In it is a bunch of things with Dovecot in it:

file://localhost/Users/marlinespike/Maildir/cur/

file://localhost/Users/marlinespike/Maildir/dovecot-uidlist

file://localhost/Users/marlinespike/Maildir/dovecot-uidvalidity

file://localhost/Users/marlinespike/Maildir/dovecot-uidvalidity.5072101f

file://localhost/Users/marlinespike/Maildir/dovecot.index.log

file://localhost/Users/marlinespike/Maildir/dovecot.mailbox.log

file://localhost/Users/marlinespike/Maildir/new/

file://localhost/Users/marlinespike/Maildir/subscriptions

file://localhost/Users/marlinespike/Maildir/tmp/

I tried restarting Mail, restarting the Mac. It still says the same thing. There have been no recent updates to any software.

Can anyone tell me how to check if the mailserver is running or how to restart it?

Thank you so much in advance.