How to Change the Default Mac OS X Mail Message Font

Indian man using typewriter

Which font sets you up for writing your best emails? Is it a clear and simple Helvetica? The somewhat playful (and much-maligned) Comic Sans? Or a creative Zapfino?

In Apple's Mac OS X Mail, you can choose a default font for both readings (plain text) and composing emails. Of course, you can also specify a default size.

Change the Default Mac OS X Mail Message Font

To specify a default font face and size for composing (and reading) mail in Mac OS X Mail:

  1. Select Mail > Preferences... from the menu in OS X Mail.

  2. Go to the Fonts & Colors category.

  3. Click Select… under Message font:.

  4. Choose the desired font in the Family column in the Fonts window.

  5. Now choose a variant, if you want, in the Typeface column.

  6. Finally, pick the desired font size in the Size column.

  7. Close the Fonts window.

  8. Go to the Composing category.

  9. Make sure Rich Text is selected under Composing: Message Format:.

    Under Responding:, preferably also check Use the same message format as the original message. This means people who send you plain text messages will get emails back in plain text from you — your default font is not used for them, but this is probably what they prefer.

  10. Close the preferences window.

What Makes a Good Font for Email?

A good font for email is one that renders shorter texts legible on any kind of screen — large monitor, tablet, phone, or watch. Typical font families and variants that accomplish this are sans-serif fonts with little ambiguity between characters, ample height for small characters (x-height), and high information density.

Fonts that encompass this and are almost universally available include the classics Verdana, Helvetica, and Arial. Choose the size that makes your text just big enough to be easily legible. Between 11 and 13 pt are typically good sizes for email. How the font is displayed depends a lot on the recipient's screen makeup and resolution; they should be able to use assistive technology to increase the font's display size if necessary.

Why Is My Default Font Not Used by Default in OS X Mail?

Have you specified a default font in your OS X Mail's Fonts & Colors settings, and you find a different font used when you start composing a message or a reply?

A number of factors can be at play here — and they can be remedied as causes for not seeing the right font.

  1. You are composing in plain text by default, the fixed-width font is used for plain text messages, and you have not altered the fixed-width font.

    Remedy: Select Mail > Preferences from the menu.

  2. Go to the Fonts & Colors tab.

  3. Either use Select… under Fixed-width font to change the fixed-width font to your preferred typeface and size or make sure Use fixed-width font for plain text messages is not checked.

    Using fixed-width fonts (such as Courier) for plain text messages is the traditional choice; it mimics the experience on early email systems and allows for ASCII art.

    Note that, with either choice, recipients of your plain text messages will not see the text in your chosen font but using their preferred plain text font.

    You can also select to compose in rich instead of plain text by default, of course; then, the Message font: choice comes into effect.

  4. You are responding to a plain-text message, OS X Mail is set to start replies with the original message's format (rich or plain text), the fixed-width font is used for plain text, and you have not set the fixed-width font.

    Remedy: Select Mail | Preferences from the menu.

  5. Go to the Fonts & Colors tab.

  6. Make sure Use fixed-width font for plain text messages is not checked.

This is probably the sanest choice. OS X Mail will still start replies using the original message's format, and when you reply to plain-text emails you still can use your preferred font face and size to write.

As an alternative, force OS X Mail to always use rich-text formatting on the Composing tab (uncheck Use the same message format as the original message) or set the plain-text font to your favorite on the Fonts & Colors tab (with Select… under Fixed-width font).