[SOLVED] All mail.domain.com's directing to one domain

[astarmathsandphysics]

I have several websites on my server with hostname server.astarmathsandphysics.com
All versions of mail.domain.com are redirecting to astarmathsandphysics.com, and I am using https so am getting certificate conflict issues, and backlinks I do not want.
I would like to redirect https://mail.domain.com/string-of-crap to https://domain.com.
I have tried using htaccess and the apache site config file
How cam I do this?

[slickymaster]

Thread moved to Server Platforms.

[astarmathsandphysics]

What I will do is this and will post if it works.
Create subdomain mail.domain.com for each domain
At the moment I am using postix/dovecot with a self signed ssl certificate. I will get a certificate from lets encrypt to replace it, and refer all subdomaINS to this certificate in their apache configuration files.

[astarmathsandphysics]

That worked.