I wonder if these people are serious. One thing to consider is that if the Devil is using email addresses he surely isn't very smart.
People change their email addresses, and frequently mail gets returned undeliverable.
Satan is going to be totally confused if he calls the roll with email addresses. There really is not a lot of standardization in email addresses. In short, email addresses are a messy proposition for the Mark of the Beast. I theorize that email address confusion is more the work of the devil. People who have lost their computer files containing all of their friends' email addresses have become violent and depressed.