Hello,
I have two domains that have their e-mail services set up through mxroute. On the actual web-hosting side, they are already set up with SSL certificates via LetsEncrypt for the domains themselves and the wildcards of the subdomains.
How do I use these certificates to set up SSL authentication for mail services? The only options I see are using automatic SSL (which appears to assume that mxroute is hosting the site?) or buying a certificate.
Most new customers will simply use this tutorial: https://mxroutehelp.com/index.php/2019/08/25/custom-webmail-pop-imap-smtp-domain/
However, as you are on a cPanel server your method is a bit different. You can go into cPanel, Custom SSL, select only “mail” and “webmail” subdomains for your domain (make sure they’re already configured as a CNAME to the server hostname for at least 2-4 hours before doing this), then click Run AutoSSL.
I discovered that there’s a page to let you install existing SSL certificates - “Manage SSL Hosts”. This let me install my domains’ certificates directly, without using AutoSSL which was outright failing.