Hello drdegroff,
It sounds like you need some help using the zoom function in email. We will be happy to help.
One method that you can try is using Shift–Command–Plus sign (+) to zoom in, and Shift–Command–Minus sign (-) to zoom back out.
The following article provides keyboard shortcuts which may help:
Mac keyboard shortcuts
Another option is to adjust your settings in System Preferences > Accesibility to control the effect zoom has so it's not zooming your entire screen. The "Use scroll gesture with modifier keys to zoom" and "Enable Hover Text" sections of the following article has more details on this:
How to zoom in or out on Mac
We hope this helps!
Cheers!