It's still a long way off from challenging Thunderbird, but it might get there soon
Geary, a lightweight email program designed around conversations and built for the GNOME desktop by the Yorba software group, is now at version 0.5.1.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.
Highlights of Geary 0.5.1:
• The ability to save sent mail has been implemented;
• Basic search operators have been implemented;
• Trash, archive, and delete operations have been separated;
• The special folder handling for "Other" accounts has been improved;
• Some IMAP issues have been fixed;
• Speed improvements and other miscellaneous bugfixes have been implemented.
You can download a source package for Geary 0.5.1, but developers say that Ubuntu users can also find a version for Ubuntu 13.10, Ubuntu 13.04, and Ubuntu 12.10 on Yorba’s PPA.
Remember that this is a development version and it should NOT be installed on production machines. It is intended for testing purposes only.