discourse/discourse — pull request #2861 by techAPJ (2014-10-08 20:14:07+00:00)
Title: FEATURE: add Precedence header

Added [Precedence](http://www.ietf.org/rfc/rfc3834.txt) header in emails where Topic ID is present (so as to avoid adding it in emails like "confirmation of accounts", "invites", etc).