Version:            (using KDE Devel)
Installed from:    Compiled sources

It's a proposal to end those debates whether mails should be hard-wraped or not.

Basically the mail body gets formated as a hard-wrapped text with all breaks inside a paragraph replaced with softer version " \n" (instead of just "\n", notice the space at the end of line). In addition to that, it requires the message having a mime type:
    Content-Type: text/plain; charset=XXXX; format=flowed

It's supported by Thunderbird, Opera, Eudora and Hotmail(!).
Find the RFC here: http://www.ietf.org/rfc/rfc2646.txt