Problem with Outlook inbox

Problem with Outlook inbox

Hi
 
I view my Zoho Mail in Outlook and it's worked quite satisfactorily until this morning when Outlook refuses to display my Zoho Inbox.  All other views are fine - the inbox is the problem.  I've verified my IMAP settings and successfully sent myself an email back from Outlook to confirm.  Is this an Outlook problem or a Zoho problem (or a user problem)?
 
Thanks