As you may know, Geary is an open-source email client, installed by default on Elementary OS, but available via the default repositories on other systems as well.
Recently, one of the Elementary OS developers has announced that Geary 0.10.0 has been defaulted on Elementary OS 0.3 Freya.
But Geary 0.10.0 can be also installed on Ubuntu 15.04, Ubuntu 14.04 and derivative systems very easy. Just follow the instructions here.
If you are new here, Elementary OS is among the most popular Ubuntu forks and the most beautiful Linux system available. Also, it has a big community that developed Elementary-specific applications.