webmail subdomain problem (npn-HTTPS)

Hi Guys!

Some of my clients have been reporting this week issues with logging into webmail (authentication failure). I found out that the reason for this is that http://webmail.domain.tld redirects them to https://cpanel.maindomain.tld, thus the login is asked for cpanel and not webmail (they didn't realize that).

I told them to use https://webmail.domain.tld which redirects to proxies (not redirect) them to https://cpanel.maindomain.tld:2096

It seemt to me that some update has changed the way http://webmail.domain.tld acts, but I don't really know how to change this back so that it would at minimum redirect to https://cpanel.maindomain.tld:2096 (this is the best, because I have a wildcard certificate for *.maindomain.tld).

Can you guys help me out?

Thanks,
Daniel