Reset Mac Mail message list font in classic view
Following a recent update, Mac Mail was displaying strangely in Classic View. I tried changing the font for the Message List, to clear the problem, and that's worked. But now I can't find a way to reset it back to the Default System font, because Default System font (or the font itself, San Francisco) is not available in the list of fonts. How can I reset it?
MacBook Pro with Retina display, OS X Yosemite (10.10.5)