The problem here is that cPanel with Apache does this :
https // webmail.clientdomain.tld
Shows an SSL error but once the certificate accepted lets you log into the webmail
On a litepseed cPanel server, it either redirects to port 2096 if the client doesn't have a SSL certificate shows an error 500 page if the client has got an SSL certificate.
Is there some way we could at least replecate how Apache runs on cPanel ?