[ChaseB]

"but when I finished I filled the BCC with as many permutations of what his email address could be and then hit send."

I've figured out a great way around this. Install rapportive in gmail, compose a new message and start guessing emails. If the email is correct, rapportive will pull up all the information for that person. Bingo! There's the correct address!

[sjtgraham]

Tried that!

[driverdan]

Rapportive only has info on people who use their service and those who have their info available on their sources (eg social networks). It's a great tool but isn't comprehensive.