Can people see the words you've written in an email?

Sometimes when I'm writing messages on the PS3 to other people the sentences tend to complete themselves, usually from the last message I've sent. It's the same with Google. If you try to type something into Google it will automatically try to complete your search based on previous entries/memory/history.

I'm wondering if this is possible with emails. For instance, is there any way someone can find out what you've written in an email by doing the exact same thing? I know we think we have full comfort in writing an email, thinking that no one can find out besides us and the recipient, but I've often wondered if we can find what's written in someone else's email i.e, is there no such thing as privacy.

Thoughts?