increase mail viewing font size???

I have been tolerating this for years and am finally tired of it as there MUST be a way to fix this that I am unaware of.

I have my MacMail set to use an 11 pt Arial font when writing messages, which is a standard font size for letters, etc. However when you are reading or writing your message, it does not DISPLAY as 11 point, but teeny weeny as if you are using a 6 point font.

Increasing this in preferences to something like 18 point simply makes your display look larger (like 11 point) but then the message your recipient gets is monstrously huge because you are really sending them 18 point type!

Why is this not a normal Apple WYSIWYG view? I don't have this issue on anything else on my Macs (viewing Safari, Quicken, Quickbooks, Excel, Word, Text, Messages, whatever - only Mail messages.

There must be a fix for this - no? I literally am to the point where I have to use a magnifying glass to read what I'm typing! LOL!

Any help is appreciated.