Release K-9 Mail v6.500 · thunderbird/thunderbird-android

What's Changed

The light and dark themes are now based on Material Design 2. This is still work in progress. (@cketti)
Added a floating compose button to the message list screen (@cketti)
Search now also considers recipient addresses (@cketti)
Always move to previous/next message when swiping left/right outside of the message body (@cketti)
Lists of folders are now sorted alphabetically in account settings (@cketti)
Added better support for right-to-left languages when composing messages (@cketti)
When sending a message, the associated draft message will be deleted immediately, bypassing the Trash folder (@schlagi123)
mailto:, matrix:, and xmpp: URIs in plain text messages are now turned into links (@cketti)
Fixed a bug where notifications would sometimes reappear shortly after having been dismissed (@cketti)
Various other bug fixes (@mhf1998, @ka7, @cketti)

Full Changelog: 6.400...6.500