Depending on the quality of your eyesight (and the font size choice of your email sender), you might find that you need some extra “help” in reading the text in a particular email. Outlook provides a couple of ways that you can easily zoom in and increase the text size of your email.
When you have an email open, you’ll see a Zoom option on the far right side of the Ribbon Bar:
When you click that icon, you’ll get a Zoom dialog box that will give you a number of options for increasing (or decreasing) the size of the text in your email:
However, if you have a mouse with a scroll wheel, it’s even easier. Just hold down the CTRL key while you scroll up (to increase the font size) or down (to decrease the font size). You’ll see the current font size percentage in the middle of the screen while you’re doing this, so you’ll know where you end up: