Moople has announced Dart (http://dart.email), a menubar app for the Mac that allows you to create and send emails with predefined answers.
The recipient just has to click a button to reply. According to the folks at Moople, there’s no worrying about composing a message, less opportunity for procrastination and no ambiguity.
You can either send a Dart message with answers you define. If you really have to send a short message, you switch to regular mode which supports a whole 200 characters
Dart requires OS X 10.9 or later. It costs US$3.99 and is available worldwide exclusively through the Mac App Store in the Productivity category.