I can email out but cannot receive emails. It was working yesterday.

I can email out but cannot receive emails. It was working yesterday.

I have tried to email from my zoho email to my yahoo email and it went through fine but when I tried to email from my yahoo email to my zoho email nothing went through but I didn't get a bounce back notice.  What is going on?  We cannot keep zoho as our business email if it keeps having problems.

Lisa