How do I change "Anonymous User" in a response file?

I'm sending a very basic form which just has 3 radio buttons and a required signature field.  There are a lot of users which are not having success returning the form with the "Submit" button, so I was going to have them just save the file after signing and send it manually though email.  Unfortunately I only see "anonymous user" in the From column of the response file, which makes figuring out who has responded a bit more involved of a task.  Is there a way to manually change this entry or somehow get Acrobat to pull the user from the signature?