Reply to messages in K-9 mail without going through the menu In K-9 (latest version on Google Play, 4.403), is there a way to either:


Add a Reply/Reply-All button to the bottom of the message details view
A gesture to Reply/Reply-All in the message details view
You need to have the latest K-9 version (4.4x).
However, it is not yet available for all devices / countries.
I installed K-9 on my Galaxy S4, and it installed 4.2x, which is not the latest.

See this XDA thread; there's a download link to the 4.4x APK, 
which you can install manually.
The newer version uses an actionbar which has a reply button.