Just say “OK, so give me the password to your email account.”
Person: (invariably) “Erm… no. Why?”
You: “I just want to read your email.”
Person: “What??”
You: “Don’t worry, I’m not going to DO anything, just read it. I’ll read it in front of you if you’re worried.”
Person: “No way!”
You: “Why not? DO YOU HAVE SOMETHING TO HIDE??”
Person: “No! It’s not dodgy, it’s just private!”
You: “Well, send it along when you’re ready. As a wise person once told me, ‘If you have nothing to hide, you have nothing to fear.’”
I’ve run this line for about 3 years and surprise! So far I have received zero passwords.
If letting someone read your email makes you uncomfortable, just imagine what that’s like on an automated, mass scale.