I am working on a mac running OSX 10.10.5 and I am using Apple mail. When I am reading an email I want to prevent the email from being marked as read instantly. I would rather mark it myself, or have it wait like 2 minutes before it marks it as read.

I know about the terminal delay trick, but that doesn't work. The Truepreview plugin hasn't been updated for a long time and doesn't work anymore. Are there any alternatives?

2 Answers 2


It is not possible by default, but you can download a plugin for the Mail app. The plugin is called TruePreview. It is said that it supports OS X Mountain Lion and below, but I had it working on my Mavericks machine.

Anyway, here's the method:

  • Quit the Mail app
  • Download TruePreview (scroll down for latest versions) and run the installer
  • Launch Mail.app and open Preferences, click on the >> arrow and select “TruePreview”
  • Adjust the Mark as Read settings as desired

Have a read on this page and you'll find that there is a Terminal command that can be used to delay the Mark As Read setting. However, I'm not sure you can disable it completely.

defaults write com.apple.Mail MarkAsReadDelay 2

Here, 2 is a measurement of the number of seconds to delay.

defaults write com.apple.Mail MarkAsReadDelay

The above will just revert the setting back to its default state.

Alternatively, if you're okay with marking it as unread, an easier option would be to use a keyboard shortcut instead of manually marking as unread. The standard keyboard shortcut, which toggles “read” and “unread”, is cmd+shift+u. You can also go to System PreferencesKeyboard to customise your own keyboard shortcut.

Have a look, see which options takes you where, and stick with whatever is comfortable. Let me know if anything went wrong during the plugin installation (that is, if you did install it).

  • Did you even read my text? I said both the Trueview plugin and the terminal defaults trick don't work anymore Commented Aug 25, 2015 at 14:50
  • Sorry, didn't read the bottom, guess I was paying attention to something else :/ but have a look at this page. I believe it should work.
    – pwn'cat
    Commented Aug 25, 2015 at 15:06
  • That's okay, it happens to the best of us ;) I will try that when I get back to work tomorrow morning and let you know if it worked. Commented Aug 25, 2015 at 15:11
  • Sadly, this trick doesn't work anymore on the newer versions of Mac mail :( Thanks anyway Commented Aug 26, 2015 at 7:34
  • 1
    TruePreview plugin is not longer available. But commands works like a charm defaults write com.apple.Mail MarkAsReadDelay 3600 just set 1 hour value that's all what you need.
    – equiman
    Commented Oct 2, 2018 at 15:23

To enable this, install the add-on Mail Act-On. Note: it is quite expensive at $32.00/€32,00, but there is a 30-day trial if you'd like to test it out.

After installing it, go to Mail.app > Preferences > Mail Act-On > Message Viewing and then you can

  1. Mark a message read after a certain delay, from 0 to 30 seconds, or

  2. Prevent messages from being automatically marked read at all.

It works on macOS Sierra.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .