due to more and more hacking issues I decided to force all my ZCS users to use HTTPS instead of non-secured http connection for webmail. POP3, IMAP and SMTP are already allowed only secured (SSL/TLS).
Now, REDIRECTING all webmail http to https works, but I have 300+ domains, and SSL certificate only for primary domain, not for all of them!
So REDIRECT issues a warning about non-valid SSL cert.
I would like to REDIRECT all requests for HTTP not just to HTTPS protocol, but to https://webmail.PRIMARY-domain.com (...instead of to https://webmail.USER'S-domain.com)