Custom URL access : domain issue

Custom URL access : domain issue

I'm trying to add a cname for custom URL access  :

Here are the steps I've done -

1. Added cname "mail" to my domain in my domain registrar control panel (not on Zoho)

2. Added subdomain "mail" to my domain in my domain registrar control panel (not on Zoho)

Now when I access mail.yourdomain.com (after all cname update ) -

that my domain does not display on all pages, in fact once logged in, it shows "https://mail.zoho.com/biz/index.do?Requested_Domain=mail.yourdomain.com" (where "yourdomain.com" is my actual domain) instead of "mail.mydomain.com/biz/index.do."

Can this be fixed or this be ??