zoho mail stopped receiving emails

zoho mail stopped receiving emails

All users (5) for my company have not been receiving emails for almost 24 hours.  I have troubleshot by sending from zoho - to - zoho, from yahoo - to - zoho, from gmail - to - zoho with very little luck.  I am receiving 1 out of every 10 emails sent to my zoho account and all my employees are experiencing the same issue.  Please help