FWIW, one of three recommendations within an IETF request for comments:
There is widespread skepticism in the technical community that labels of any sort will be effective. Such labels should probably be avoided as ineffective at best.
<
http://www.diigo.com/04qmv> for a highlighted view of <
http://tools.ietf.org/html/rfc4096>.
If users (of the Nabble forum) opt to subscribe to the forum, or any part thereof, via e-mail: will they be surprised by the absence of a
[xxx] prefix?