Changes in v5.000 RC1:
- K-9 Mail now requires at least Android 4.0.3
- Added support for OpenPGP API v3 (get OpenKeychain)
- Added ability to use client certificates for authentication
- Enabled support for TLSv1.1 and TLSv1.2
- Added SSL/TLS session caching
- Offer encrypted connection by default when manually setting up an account
- Simplified options for authentication and security
- Removed auto-configuration settings for all providers that didn't support encrypted connections
- Added privacy setting to omit the User-Agent header
- Added privacy setting to use UTC as timezone in mail headers
- Finer grained control for notifications
- Added support for delete confirmations in the message list
- Added the option to show the password when setting up new accounts
- Added a slider to allow picking a font size for the message body (40% to 250%) in settings
- Added support for KitKat's Storage Access Framework that allows you to attach multiple files at once
- Multiple bug fixes
- Updated translations