Rated 5 out of 5 stars

There is a NEW version, but whatever the reason it has been not updated here. It's version 0.4.3, updated on June 16th, 2008. It's compatible with 2.0x, makes header substitution simplier -no need to specify any text, now it makes it automatically- and allows to select date format. It's available here, among other places:

http://mac.softpedia.com/get/Internet-Utilities/ThunderBird-Reset-Quote-Header.shtml

Saluditos,

Ferrán.