Customizing Font Sizes
For those who use email on a regular basis, it's important to be able to comfortably read what's on the screen. Most of the text within Postbox can be adjusted to meet your needs, however some are more tricky to change than others.
Postbox Interface Fonts
You can choose between three interface font sizes which effect the Folders Pane and Message list. To change the interface font size, go to:
Mac: Postbox > Preferences >Display > General
Windows: Tools > Options > Display > General
and choose between Small (11px), Medium (12px) and Large (14px) sizes.
Message Fonts Display Font
The Display Font in Postbox controls the size of non-HTML formatted messages that you receive, as well as when you're composing a message yourself. Changing this does not affect how the recipient views your message. In other words, the Display Font is just for you.
To change the Display Font, go to:
Mac: Postbox > Preferences > Display > Formatting
Windows: Tools > Options > Display > Formatting
Here, you can choose your preferred font (measured in px), size and color.
The Composition Font determines how the recipient will see their message. You may choose whichever font you'd like, but if the recipient does not have a certain font on their computer, it will revert to a default sans-serif typeface.
To change the Composition (message) font, go to:
Mac: Postbox | Preferences | Composition | General
Windows: Tools | Options | Composition | General
Here you can change the font, text color and background color.