[nercht12]

I wish Thunderbird would show me the email address of the sender without requiring that I open the email. That way I could check for spammers and fakes posing as friends. I've searched for such a feature and haven't found it yet.

[IgniteTheSun]

Control-u shows the message source - you can see the email address there without opening the mail.

(For a little bit of security when opening an email, one can also turn javascript off in Thunderbird. I've never seen why anyone would javascript in email - anything requiring javascript would probably be better done in a browser in my opinion.)