Read And Enjoyed But No Comment. A possible and all too frequent mailing comment in an APA. Means just what it says - the person read it, liked it, but didn't have anything more to say about it. Because it does not foster further discussion, it is often referred to as the dreaded RAEBNC.
Variations, such as RAHBNC (Read And Hated But No Comment) and RAEBNCH (Read And Enjoyed But No Comment Here i.e. elsewhere within the APA it exists, or possibly it arrived via email) exist but are much rarer.
Interestingly, RAEBNC is rather analogous to an upvote here on E2. Which causes me to wonder -- Does Everything have the APA nature?