Address bar to read "mail.mydomain.com" after logging-in

Address bar to read "mail.mydomain.com" after logging-in

Despite creating and using the custom login page , the address bar still does NOT show "mail.mydomain.com" after logging in.  It still shows "mail.zoho.com" when in "inbox".  Please see the image below:


 



I already created custom login URL using the steps indicated in below link:


However, it does not solve the problem indicated above.  Thank you for your help.