Geary, a lightweight email program designed around conversations and built for the GNOME desktop by the Yorba software group, is now at version 0.7.0.The software is developed by Yorba, the same team responsible for Shotwell, a photo manager that is the default application in major Linux distributions such as Ubuntu and Fedora. The project was recently adopted into GNOME and now the updates seem to arrive a little bit faster.
According to the changelog, a major overhaul of the email composer has been implemented, the inline in main window has been redesigned, the composer will automatically add signature to emails, saving drafts to a server can now be disabled, and the main window interface has been improved with the help of GtkHeaderBar.
Also, various database speed optimizations have been implemented to reduce lags and to improve read times, the connection retry function has been improved, and numerous other smaller bug fixes have been implemented.
You can download a source package for Geary 0.7.0, but the developers provide for Ubuntu users a stable version via a PPA for all the supported versions of the operating system from Canonical.
Remember that this is a development version and it should NOT be installed on production machines. It is intended for testing purposes only.