Even if nobody you email uses PGP themselves, you can still get a lot of benefit from encrypting your email: https://grepular.com/Automatically_Encrypting_all_Incoming_E...

Even if you think that your email is unimportant and you've got nothing to hide, you probably still don't want people being able to use your email account to take over your other accounts (password reminders) if they get access to it.