Specifying Minimum Font Sizes in Apple's Mail.app

I get a lot of email, and as is the current fashion, a lot of is formatted in what’s called Rich Text (which generally means HTML). And in the same way that a web browser formats HTML into a pretty web page, your mail client is doing the same thing for the HTML-formatted email you receive.

Most of the email I receive looks just fine, and is rendered in Mail.app’s default 12pt Helvetica. Sometimes though, I’ll get an HTML-formatted email that appears in an incredibly small font. These emails are usually from Windows users (you can tell this by reading the message headers, which geeks like me actually do sometimes), who seem to have a different sensibility about what font-sizes are legible.

Usually these emails are from website visitors who are writing to ask me for help with a tutorial I’ve written, so being able to actually read their email is important to me.

In the past, I’ve used a built-in key-combo (Command-Option-P) to tell Mail.app to render the message using the plain-text version, which is usually embedded in the message. This is a bit of a pain when you receive as much poorly-formatted email as I do, so I went looking for an alternative.

The first answer I found detailed a way to force Mail.app to always render the plain-text version of the email by quitting the app and then entering the following command in a Terminal window:

defaults write com.apple.mail PreferPlainText -bool TRUE

You can change this setting back by changing the TRUE to FALSE and re-issuing the command (Mail.app can’t be running as it will overwrite these settings with those in memory when it quits).

After you relaunch Mail.app, you’ll see the plain-text version of any HTML email you receive by default. Of course this only works when there is an embedded plain-text version, but that’s usually the case. In my experience though, I found that I actually do want to see the HTML-version of the mail, when receiving newsletters I subscribe to, or when viewing project-related emails where formatting is important, for example.

A better option would be to set a minimum font-size, just like we can do in a web browser. Jonathan Eckmier had the answer for me. You can use a hidden Mail.app preference to set a minimum font-size by quitting the app and entering the following command in Terminal:

defaults write com.apple.mail MinimumHTMLFontSize 12

Once again, you can always switch this setting back by changing the 12 to a lower number (perhaps even 0) and re-issuing the command (and again, Mail.app must not be running).

I set my minimum font size to 12, but you can set and change the number using the above command any time you like. Once you’ve made this change, every font displayed in Mail.app will be set to your minimum size or larger, but you’ll still see those pretty HTML emails just as you would have before.

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