permanently set font?

permanently set font?

I'm new, and apologize in advance if I've missed something obvious.  But is there a way to permanently set font size/color? Me and most of my friends have bad eyesight, and increasing size/changing color on every email is a serious pain.

My ideal would be to have all incoming mail in 14 pt black, and all outgoing in 12 pt blue.  Is this possible?  If not, can I set both in and out to 14 pt.?