I'd even condense it further:
If you are really pissed off by a mail, sleep over it before you reply.
The more you are pissed off, the more let it settle for a while.
This is even law in many places like in german, austrian or british
armies:
https://de.wikipedia.org/wiki/Milit%C3%A4rische_Nacht
/Manuel
--
Wikimedia CH - Verein zur Förderung Freien Wissens
Lausanne, +41 (21) 34066-22 -
www.wikimedia.ch