
We originally hinted at it in 2009, but as it has been a long time and the project is still on the air, it is worth repeating: with the QuoteFix, you change some of the original Mac Mail behaviors to improve your responses.
The plugin positions the reply cursor below the original message (instead of before it), tries to remove the original signature, removes unnecessary blank lines, can optionally remove old email quotes, among others.
The open source project is in its 2.7 beta 3 version already compatible with OS X El Capitan. Some problems still need to be fixed, but it is already "usable".
Here's the tip!
(via Mac Kung Fu)