Contact who wants mail is in Do-Not-Mail; can't restore

Contact who wants mail is in Do-Not-Mail; can't restore

I have one contact in the Do-Not-Mail list who actually wants our campaign mail. The contact can't be added in the ordinary way.

Another message here said to put the contact into an Excel file and import it. Zoho refuses to add the contact, even as an import from Excel, because it's in the Do-Not-Mail list.

How can this be fixed?