Mail Box (yourmailID) you have configured earlier is not reachable. Please select a new "Mail Box".
One of the instances why this message will display is when you change the Default Email ID in your Zoho Mail settings (Settings > Custom Settings > My Preferences).
The Zoho Mail server is currently unavailable. Please try after a while
Emails will not be displayed if the mail servers are not accessible. In the event of this scenario please wait for a couple of minutes before you try accessing your email.
Your account status in Zoho is still not confirmed
If your account status has not been confirmed/verified in Zoho, then mail will not be displayed. Please do the following to confirm your status:
Your email is queued in Zoho Mail - Outbox
The Outbox option keeps your Emails in queue for a specified time interval before sending from the Zoho Mail. If you enabled this option, sent Emails will be listed under the Emails section after a few minutes.