SSL-Certificate Verification for hosted mail-server domain

Hi Till,
first of all, I need to say that ISPconfig is an awesome tool and I like it very much. Everything works fine besides a small issue I am fighting with. Maybe you got a tip for me:

I set up the webserver with a unique domain (let's use "serverdomain.com" as an example for this) and generated a LetsEncryppt - SSL-Certificate for it and also one for the Server-Subdomain "server.serverdomain.com", where ISPconfig is hosted.

I now set up 2 domains in ISPconfig and also Email-Accounts for each domain. And I also generated a LetsEncrypt - SSL-Certificate for these domains, which is working fine, when calling the domain with the browser. And according DNS-Entries A and MX for "mail.hostedcustomerdomain.com".

Problem is, when I want to set up the email-account in, let's say, Outlook, and I enter the "mail.hostedcustomerdomain.com" for IMAP and SMTP-Server when setting up an email, let's say "emailaddress.hostedcustomerdomain.com", I get the following SSL-Warning:

"The server, which you are connected to, uses an SSL-Certificate, which cannot be verfied. The target-principal-name (Zielprinzipalname) is not correct. Do you want to use this certificate anyway?"

When I enter the Server-Domain "server.serverdomain.com", there is no warning. So it seems, mail-service always uses the SSL-Certificate of the serverdomain.

How can I set up that the server uses the respective customer-domain ssl, when setting up email-service and dns-A-MX record for this customerdomain?

Thanks for your valued help.

Best,
Johannes

 

Hi Till, thanks for your fast reply.

I already searched for such threads before writing mine and did not find a matching thread.

Can you provide me a link to such a thread. This would be really helpful to me.

Best,
Johannes

 

Thank you very much, Till. Your support is really awesome, like your ISPconfig-System.