This is exactly what i have done , i was also getting weird error message about the code of Country so i also removed the phone number and leave it blank and in letter of explanation i gave them the phone number just in case if they have to call my wife for some reason , Phone number that i entered under my info worked fine but for my wife info it did not . so i remove it , Not a required field so you can leave it blank .I removed all the phone numbers for both sponsor and co-signor (since its not a required field) and added only email addresses for both. The form is fine now and Validation Status has remained to "Yes".