Supress notification per post

I'd like the ability to supress notifications on a per post basis, so regardless of the users setting it ensures that a notification isn't sent if the post includes a certain keyword - to be used by anyone when they post a message that they know doesn't warrant a notification to those who have it setup.

For example, if a channel posts announcements it may make sense for the users to have their notifications setup for that, but if someone asks a question about that post in the same channel then it doesn't necessarily warrant a notification being sent to everyone who has them enabled.