Lucy Burroughs answered
You shouldn't be trying to read your boyfriend's emails. That's a violation of his privacy and is just immoral. If you're having relationship problems or suspect him of cheating, then talk to him about it. How would you like it if you found out that your boyfriend been reading your emails? It's likely that you'd feel angry and violated, and would probably want to break up with him.
The fact that you want to sneak into your boyfriend's email suggests that you don't trust him. If you'd do that to him, he shouldn't trust you either - and if trust is that absent in your relationship, you shouldn't be together. Trust is integral to any relationship - maybe you should find someone who you do trust.
There's a reason these things are password protected - it's to stop people other than the intended recipient from reading them. Without acquiring the password or catching him logged in, you're not going to be able to read his emails - and it's wrong for you to even attempt to.
The fact that you want to sneak into your boyfriend's email suggests that you don't trust him. If you'd do that to him, he shouldn't trust you either - and if trust is that absent in your relationship, you shouldn't be together. Trust is integral to any relationship - maybe you should find someone who you do trust.
There's a reason these things are password protected - it's to stop people other than the intended recipient from reading them. Without acquiring the password or catching him logged in, you're not going to be able to read his emails - and it's wrong for you to even attempt to.