This reverts commit a889c683ddd333dde80c52c722095426233a482f. Sorry, I pushed to the wrong branch. :-(
Version 3.x has been stable for a long time; let's give up support for the obsolete versions.
probably be a bit tricky, due to sendmail "compatibility" (postfix makes a symlink to "sendmail", so programs will keep on working). svn path=/nixpkgs/trunk/; revision=5030