Q A couple of preference settings, controlling automatic correction of spelling errors and ‘from’ addressing, that I have made in Mail keep becoming undone whenever I restart my Mac mini. How can I get them to persist properly?

A This can happen when Mail’s preference file, at ~/Library/Containers/com.apple.mail/Data/Library/Preferences/com.apple.mail.plist, has incorrect permissions set, or has become damaged, so that changes to it cannot be saved properly.

The first should be rectified by repairing permissions using Disk Utility.

Next make a careful note of your intended settings, then locate that .plist file and move it to another location such as your Documents folder. Restart, open Mail, and set its preferences to your taste: they should now stick.

Comments Whenever any app’s preferences settings cannot be changed, suspect that the property list (extension .plist) file containing those settings has become damaged, or has incorrect permissions set, so that the new settings cannot be written out to it.

The most difficult task is usually locating that settings file. Traditionally all preference settings should be stored in ~/Library/Preferences, but apps which are delivered through the App Store, including components bundled in OS X, now normally run in a Sandbox, and their settings are stored in an elaborate hierarchy in ~/Library/Containers instead.

Once you have moved the damaged file away, when you next start the app it will create a fresh property list to contain its settings, which should work properly again.

If the problem keeps recurring, it suggests that something else – perhaps a third-party service that you have installed – is deliberately messing with the settings, and corrupting the property list. Look first then to any enhancements or utilities which could be doing that.

Updated from the original, which was first published in MacUser volume 30 issue 05, 2014.