https://lists.debian.org/debian-ocaml-maint/2017/01/msg00014.html
Bug#850071: tuareg-mode: Fail to install if emacs21 is installed.
bugtuaregmodefail
https://lists.debian.org/debian-testing-changes/2007/12/msg00027.html
Accepted emacs21 21.4a+1-5.1+lenny1 (source all i386)
acceptedsource
https://lists.debian.org/debian-emacsen/2002/01/msg00002.html
w3m & emacs21 problem
problem
https://lists.debian.org/debian-emacsen/2006/10/msg00047.html
Re: emacs21: annoying black side stripes
black sideannoyingstripes
https://lists.debian.org/debian-security-announce/2005/msg00063.html
[SECURITY] [DSA 685-1] New emacs21 packages fix arbitrary code execution
securitydsanew