In continuation to our efforts in protecting your Zoho Mail account we have made a few changes in the custom login page. We are making some enhancements in the browser to server communication to make it more secure. 

You may be aware of the most of the modern web browsers mandate certain security practices to showing the webpages as 'Secure'.  We are rolling out the security related enhancements ensure that our custom login page accessed only in https mode and the authentication is securely done at our end(accounts.zoho.com). 

This is a mere announcement applicable to users who already use custom URL and to keep them posted about the changes. There are no changes needed in the existing configuration or settings related to using Custom URL. Similarly there are no additional certificates needed for using the custom Login page. These changes will be rolled out on 4 March 2019. 

Please feel free to post your questions as comments below.