If you have a older Mac that doesn't support pinch gestures or you just prefer keyboard shortcuts, a simple Command-+ (that is Command and the plus sign together) will increase the size of the text and Command-- (Command and the minus sign together) will decrease the text size.
The zooming works a little differently in Mail than Safari:
- In Mail, the the text size increases and and decreases but any images and most formatting stay the same. This helps keep the look of the email together while making it easier to read.
- In Safari, zoom increases all of the objects on the page in proportion. This keeps the formatting of the webpage exact, but you quickly have to scroll right and left to see the entire page.
There are actually three kinds of "Zoom" in OS X. You can:
- Zoom objects like in this hint. You can also just the pinch gestures in iPhoto to zoom in and out of a photo.
- Zoom the size of a window (similar to Maximize on the PC)
- Zoom the entire screen