Hi Sellerone,
My apologies, I should have been more clear on this, but Tristan is right. It would have been better if I typed mail.userdomain.ext instead of mail.domain.ext, because this is what I actually ment...
So I registered a certificate for servername.serverdomain.ext (with all other subdomains that are registered automatically like www, mail, ftp, pop3 and smtp), but when a customer wants to send mail using mail.userdomain.ext, then the problem occurs that the certificate does not match. Like mentioned earlier in this thread in april, surely I can add more domains in the ca.san_config. But the I have to do this all manually and what about all domains that my customers add themselves in DirectAdmin? It's not likely I will see all newly created domains instantly so I can't quickly add them manually to ca.san_config (and I don't want to, actually).
Second possible problem with this "workaround" is that a certificate is limited to 100 names and I can imagine that amount is insufficient for some admins...
So it would be nice if there could become an option to use the certificates for userdomain.ext within Exim (the name mail.userdomain.ext can be found in most LE-certficates for userdomains in the end)...
Regards,
Danny