We have just migrated to Zoho Mail and seem to be receiving a few 'blank' emails.  Initially we thought this was just one or two users but it's becoming a bit of an issue.  

One common theme we have noted is that hosted Exchange accounts emailing us seem to be affected the most.

I know there are some very old threads on this, but is anyone aware of a cure?  Otherwise I fear it might be the end of our Zoho Mail experience.