Can't Delete Mail from Email Client

Can't Delete Mail from Email Client

Hello, and thanks for Zoho service. For the most part I have been really satisfied.

One thing I am unable to do, however, is delete mail from my email client. I think one day I deleted a folder or two by mistake which may have something to do with it.

The error I get is: "An error occurred while moving message to mailbox(null)."

I've attached an image of error message below which occurs when I click the 'Delete' button with a message selected.