Diablo (I think we are on first names now, right?

) Thanks for your well-worded and coherent reply.
I am aware that many email programs do use the fonts the user determines, but others allow you to use the formatting the sender uses. Personally, if someone goes the the trouble of trying to make an email attractive and easy to read, I will allow that. But if they use silly stationary and a lot of excess junk, I don't care for that. Some do, I know. That's certainly their privilege, but it's not for me.
I have heard that saying about serif fonts being easier to read for decades now. But, I have yet to see even one study showing it to be true. As making technical manual, or anything else, easy to read and understand has been a concern of mine, I have put quite a bit of effort into fonts and those studies seem to be, shall we say, "elusive"?
I know that most people have figured out that Macs and PCs are simply devices to crunch ones and zeros. If one is good at doing them for spreadsheets, it will be good at doing them for graphics too and vice-versa. But it was only yesterday that I received an email criticizing my choice of a Mac and showing Mac games as a Mario brothers type of 2D game and a PC game as a screen shot of WoW or something similar. This was from a person who should have known better but a lot of people still buy into old, unsubstantiated things even though the evidence otherwise is overwhelming. That reminds me of one of my Universal Truths. "Man's most precious possessions are his illusions. He will often sacrifice his belongings, his family, and even his life before his illusions."
I respect your right to like or not like a particular font. I also agree that using too many fonts in any document is counter-productive to good communication. For that matter so is excessive use of emphasis such as italics, bold, or underlining. When too many things are emphasized, nothing stands out. That is one of the first things I have always had to teach beginning writers.
I see the a similar thing in amateur videos. Every change in scene is done with a different transition effect. But if you watch professional videos and movies, you don't see many transitions at all and very rarely something like screen wipes, swirls, and the rest. A very short overlap fade is what is used most often and even that, not very much.
So it's very true what you say about just because something is available, it doesn't mean you should use all of it. They are there to provide a choice, not to see how many you can include in one short document or video.
As we say here, Cuprimentos,
Jim