Horizon Mail works best with local clients, such as Thunderbird, a fully open-source email client. While Horizon offers a Webmail client, it is not recommended for regular usage.
This tutorial will help you setup Horizon Mail with Thunderbird.
DO NOT ATTEMPT TO SETUP HORIZON MAIL ALIASES WITH THIS TUTORIAL!
Horizon Mail aliases are virtual addresses which forward all incoming mail to your main inbox (your primary Horizon Mail address), and work as a proxy for sending messages as the alias address. They DO NOT need to be setup as separate accounts and work out of the box once you create them in the Horizon Mail Dashboard.
Horizon Mail Aliases Thunderbird Tutorial
Head to Thunderbird's Homepage and click the "Free Download" button.
Windows and macOS have very easy-to-use installers. Simply follow the written instructions on each step to install the app.
On Linux, Flatpak is the preferred platform for Thunderbird because it is easy-to-use and is up to date with the latest security fixes and feature updates.
sudo apt update
sudo apt install flatpak
sudo apt install gnome-software-plugin-flatpak
This will integrate Flatpak into the Ubuntu Software app, allowing easy installation and updating of Flatpak apps.
flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
This will add the official Flathub repository to Flatpak, giving you access to the biggest library of Flatpak apps.
flatpak install flathub org.mozilla.Thunderbird
On first installation, you may be prompted to add an existing mail account. If you do not see the prompt, please do the following.
Thunderbird Hamburger Icon
Thunderbird Account Actions Button
Example of Account Setup Screen
This section can be any name you would like to be shown in your outgoing mail. This can be your first name, full name or online alias for example.
This should be your full Horizon Mail address.
This should be your Horizon Mail Dashboard password.
Thunderbird will make an attempt to find configuration, but will probably fail. In the event, use the following information.
Example of Manual Configuration
While we use “Normal password” as the authentication method, Horizon Mail hashes passwords server-side using SHA512-CRYPT.
Both incoming and outgoing servers will use secure connection methods to prevent interception from client-to-server. Horizon Mail does not allow insecure connections (non SSL/STARTTLS).
Once filled out, click Done.
Now that you've setup Horizon Mail, let's make sure our configuration is working correctly.
Navigate to Is My Email Working? and input your Horizon Mail address.
After clicking Check!, you should receive an email from IsMyEmailWorking and see it in Thunderbird.
Message from IsMyEmailWorking
Reply to this message with any body, but keeping the subject intact.
Within a few moments, Thunderbird should receive a second message from IsMyEmailWorking saying that they received your sent message.
If both tests work, that means you've successfully setup your Thunderbird to work with Horizon Mail.