OpenSubject is an public project to make email correspondence more efficient through the use of simple 3 letter codes. Instead of using your project name as a subject for every message you sent you enter a code which says something about the contents or tha message and the desired action to be taken by the receiver. Example Subject: NRN: Project X Information Means: NO Reply Needed: this message contains information about Project X With their own list of three letter codes they give some good hints to start with this. Big issue: How to remember the codes?