Email, Messaging, & Video Calls Email How to Change the Default Font in the Mac's Mail Program Choose your favorite font and size for emails By Heinz Tschabitscher Writer A former freelance contributor who has reviewed hundreds of email programs and services since 1997. our editorial process Heinz Tschabitscher Updated November 19, 2019 Email Yahoo! Mail Gmail Tweet Share Email Which font sets you up for writing your best emails on your Mac? Is it a clear and straightforward Helvetica? The somewhat playful (and much-maligned) Comic Sans? Or a creative Zapfino? In Apple's Mail application in macOS and OS X, you can choose a default font for both reading plain text and composing emails. You can also specify a default size. Information in this article applies to Macs running macOS 10.15 Catalina and all previous versions of macOS as well as many of the OS X versions. Change the Default Mac Mail Font To specify a default font face and size for composing and reading plain text mail in the Mac OS X and macOS Mail application: Launch the Mail application and select Mail > Preferences from the menu bar. Go to the Fonts & Colors tab in the preferences screen. Next to Message font, click Select. In the Fonts screen that opens, select the desired font in the Family column. Choose a variant in the Typeface column and pick a font size in the Size column. Close the Fonts window. Click the Composing tab in the Fonts & Colors preferences screen. In the Composing section, confirm that Rich Text is selected next to Message Format. Optionally, in the Responding section, check Use the same message format as the original message. When people send you plain text messages, your replies are in plain text as well—your default font is not used. Force Mail to always use rich-text formatting on the Composing tab by unchecking Use the same message format as the original message. Close the preferences window. Changing a Mail Font on the Fly Even if you establish a default font you want to use when composing emails, occasions may arise when you prefer using a different font for all or part of the email. Type the email text and then highlight the part of the text you want to change. Format the selected text by selecting a font, size, color, or other attributes from the formatting bar at the top of the screen. Formatting changes are only available for the body of the email message, not for the To, From, and other header fields. What Makes a Good Font for Email? A good font for email is one that renders texts that are legible on any screen—large monitor, tablet, phone, or watch. Typical font families that accomplish this are sans-serif fonts with little ambiguity between characters and ample height for small characters (x-height). Classics Verdana, Helvetica, and Arial are fonts that encompass these features and are almost universally available. Choose the size that makes your text big enough to be easily legible. Between 11 and 13 points are typically suitable sizes for email. How the font displays on the recipient's display depends on the recipient's screen makeup and resolution. If they have size problems, they can enlarge the email type on a case-by-case basis or use assistive technology to increase the font's display size permanently if necessary.