Can we get a tooltip of someone's email address when hovering over From field in the main Mail view?

Can we get a tooltip of someone's email address when hovering over From field in the main Mail view?

It would be helpful to be able to see the email of a sender without opening the message!  Can we get a tooltip for that when we hover over the From?  I don't want to open any spam by mistake but I also don't want to miss legitimate messages.

Also, once we DO open a mail, we should be able to see the subject line easily.  Right now I think all we can do is open the header and that's very hard to read in the format it's in currently.