Zoho account not receiving messages from yahoo account

Zoho account not receiving messages from yahoo account

Hello,

I just signed up for a free personal ...@zoho.com mailbox.  I sent test messages from my zoho account to my yahoo and hotmail accounts, and from my yahoo and hotmail accounts to my zoho account.  My zoho mailbox never received the messages from my yahoo account.  Since I sent those test messages, I've logged off and back on to my zoho account at least twice.

The other three tests worked (zoho to hotmail, zoho to yahoo, and hotmail to zoho).

What might be the trouble?

Thanks,
Dan

PS Thank you for this service.  The absence of advertising is a great relief.