Deactivate automatic mark as read in Apple Mail 7.3 I just changed from Windows to OS X Mavericks with Apple Mail App 7.3. The first thing I'm wondering about is that I cannot disable the automation to mark an email as read by default when I just clicked on it. Is there any way to do so?

I found TruePreview. But the tool does not support Mail 7.3 any more. Another solution would be to use a different mail client like Thunderbird. But there I miss the integration of the address book and the synchronisation with my iPhone and iPad.
I've been using Mail Act-On. It's overkill (does a lot more than just keep messages unread) and kind of pricey at $30 (with free trial), but since it's a paid app, they keep it up to date. Even when TruePreview was being maintained, it'd sometimes be weeks or months before it was updated to work with the latest version of OS X.