I’m on Mojave 10.14.6. I use getssl 2.14. I’ve been using getssl for a couple of years now.
For a while, Mail.app has been complaining about the certificate on my mail server (my own, which I run on a VPS) whenever I update. I have been able to override this, but I can’t remember exactly how I did this previously.
In any case, I was only able to get around this today by rebooting my Mac. Restarting Mail did not work.
I hope this helps others, and if there is a better way, I would appreciate hearing about it.
God bless you all.