Cannot send or receive email to username@zoho.com address - DELAYED

Cannot send or receive email to username@zoho.com address - DELAYED

EDIT - zoho mail is DELAYED in sending and receiving.  It took 3 hours...

My internet mail sends and receives mail just fine.  Emails initiated from within the Zoho Contacts Module AND composing the email tab are not being sent or received using the username@zoho.com account.  Please let me know what I can do to remedy the situation.  The email templates are critical to my business.  Thank you very much.