The current version of Geary is 40.0
Using GNOME Software
If your computer came with the Software app pre-installed, simply launch that, search for Geary, and click Install.
Using a package manager
Most Linux and BSD distributions provide packaged versions of Geary, ready to install. Launch your computer's usual software manager app or package manager and search for Geary there. Consult your computer's online documentation for further help installing packages on your computer.
For Ubuntu and Debian based distributions, try running the following from a terminal window:
sudo apt install geary
And for Fedora:
sudo dnf install geary
Note: Distributions with time-based or long-term-support releases may have out-of-date versions of Geary. To make sure you have the current version of Geary, install from Flathub instead.
These methods require some technical knowledge. If you get stuck, ask for help.
Nightly Flatpak builds
You can install a nightly build of the latest development version of Geary by running this command:
flatpak install https://nightly.gnome.org/repo/appstream/org.gnome.Geary.Devel.flatpakref
This will install in parallel to the stable release versions, so you can run both at the same time.
Note: The usual disclaimer about running development versions of software here applies, but in particular remember that if you are using Geary nightly you are also getting the whole unstable GNOME stack, so problems you see with the Geary nightly may also be caused by libraries such as GLib or WebkitGTK.
As such, if you are going to run nightly as your daily driver, please consider installing both coredumpctl and debug sumbols for both Geary nightly and the GNOME master SDK so that you can get decent stack traces from a crash and report crashes to the right component.
Installation from Source
To install Geary from source code, you can download release tarballs, or clone and build the latest development code from Git:
See the BUILDING.md file in the source tree for source installation instructions.