Domain is hosted on Cloudflare and web site must point to some other web server. I will only host mail accounts on ISPConfig. I have installed ssl for ispconfig hostname itself (server.domain.com) and can use that hostname ssl for mail clients incoming and outgoing server names. But I want to use mail.domain.com ssl name. So how can I do that?
I'm not sure I understood correctly what you wrote, but I assume you want e-mail server with FQDN mail.comain.com? Easiest way to achieve this is use that as hostname when installing the host. If you for some reason really need server hostname server.domain.com and e-mail server hostname mail.domain.com, you can do this by changing the hostname in Postfix setup files. To get certificate for mail.domain.com, the usual tutorial by @ahrasis works.
I had to create website with hostname mail.domain.com and able to use certboot to create ssl and set it in postfix with that hostname and pointed to those ssl paths. And it seems ok now.
