Create a release with Adobe Sign always bounces

I'm uploading an image that includes a person so I need a model release.  I'm trying to use the Adobe Sign feature to create a release for this person.  It always says it has sent an email to the person and a while later always says the email bounced.  I've verified the emal address by just sending a normal email and they do receive it.  Don't know why the status always gets changed to "email bounced".  Don't know how to get a release signed in a way that is easy for the subject who I will not see again and my only contact is their email address.