January 2014 onwards, Internet's governing body ICANN requires domain registrants to

IMPORTANT: Domains will be disabled, if you don't verify them, From January 2014 onwards, when you register a new domain or transfer existing domains or change the registrant (owner) or email address on your contact information, you will receive an additional email with an activation link. You have to press this link. If you don't press this link, your domain will be disabled after 15 days.
If the verification is not completed within 15 days, your website will be replaced by a website displaying a verification error as shown below:

This Domain Name is Suspended
The domain name you have entered is not available. It has been taken down because the email address of the domain holder (Registrant) has not been verified.
If you are the Registrant of this domain name, please contact your domain registration service provider to complete the verification and activate the domain name.

Note: It may take upto 48 hours after verification for the domain name to start resolving to its website again.”
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Don’t panic if you see the above error. All you have to do in click on the verification email link sent to you and the website will be restored – but it may take upto 48 hours for your website to be visible again due to propagation issues.
Note: Mumbai Hosting plays no role in the verification / suspension process and these activities are directly controlled by ICAAN. Whenever you register, transfer or change your details, please ensure that your domain name is associated with a valid email address.