So I've discovered one of my friends is gay, or at least bisexual, What should I do?

When I say I discovered, I kinda did some snooping into his emails and found some stuff out so it is safe to say he is one of the closeted ones. So my thing is should I tell him I know? And reveal that I've been snooping into his personal life or should I just say nothing, and keep quiet? Please no answers about how I'm an immoral person for snooping, unless it pertains to a real answer.