Unable to connect to messaging server.

Unable to connect to messaging server.

I send mail from a test Gmail account and a couple of others to my Zoho mail account. Using the Zoho mail web interface, I check for the mail, but the mail never arrives. I see a message at the top of the screen:

Unable to connect to messaging server. Connecting in XX seconds. Try now.

It never connects.

I am able to send mail out from Zoho successfully.