Stopped receiving email on Android devices

Stopped receiving email on Android devices

Earlier this week, I stopped receiving incoming emails on both my Android phone and tablet. The devices are telling me that the email app is not authenticating and instructs me to change my settings, which currently are as follows:

Server: msync.zoho.com
Port: 443
Server type: SSL/TLS (Accept all certificates)
Client certificate: None

I have not changed my password or username, so I am at a loss as to why I would have suddenly stopped receiving email on Android devices. Can you help, please?

Thanks!