Just a note, I don't think SSRS cares about the email address when it creates a snapshot. A bad email wouldn't cause it to not create the snapshot. That's why I'm asking if you double-checked what you typed for the email address in the subscription. I've done that before, typo'd one letter and not caught it. But if you've already double-checked the email address in the subscription to make sure you didn't mistype it...

How many people are you sending out the snapshot to? Just one? Or are there multiple email addresses?

If multiple, how are you separating out the email addresses from each other?