LXLE is a rather interesting Linux choice for email work. It is based on Ubuntu, but it is tuned specifically for older or modest hardware, and that changes the conversation when choosing a mail client. On LXLE, you are usually dealing with a lightweight LXDE-style desktop, conservative resource usage, and a user base that often wants reliability more than novelty. That means the best mail clients are not necessarily the most feature-packed ones, but the ones that start quickly, integrate cleanly with GTK-based desktops, and do not ask too much of the machine.

Because LXLE uses Ubuntu package foundations, the natural first stop is APT with .deb packages. Flatpak is also often a sensible option if you want newer application versions without disturbing the base system too much, though on very old hardware it can add a little overhead. Snap is available in Ubuntu-land, but on LXLE I would generally avoid it unless there is a specific reason, because its startup and integration are not usually the most elegant choice on lightweight systems. In practical terms, for LXLE I would prioritise clients that are available as .deb or flatpak, keep resource usage modest, and fit well with a simple desktop workflow.

For this distro, the most suitable clients from your list are:

• Thunderbird
• Evolution
• Geary
• Proton Mail
• Tuta Mail

If I were narrowing it down for a typical LXLE installation, I would say Thunderbird is the best all-rounder, Geary is the lightest pleasant daily-driver option for simpler accounts, and Proton Mail and Tuta Mail are the obvious picks if you actually use those services. Evolution is excellent if you want deep calendar and contact integration, though it is a little more demanding and GNOME-oriented than the other choices.

There are other clients in your list that are certainly usable in Linux generally, but on LXLE they are less compelling. Betterbird is technically attractive for people who want Thunderbird with refinements, yet the tar.xz-only distribution is not as neat on an Ubuntu-based system where native packages are simpler to manage. Mailspring has a modern interface, but it is not my first recommendation for a light desktop because it tends to feel like more software than you need. KMail / Kontact is powerful, but LXLE users usually prefer something less desktop-environment-specific. Claws Mail is absolutely worth mentioning for speed and efficiency, though it suits users who do not mind a more utilitarian look and a slightly more manual setup.

On LXLE, the three best choices in most real-world cases are:

1. Thunderbird for the best all-round compatibility.
2. Geary for a simpler, lighter desktop experience.
3. Proton Mail or Tuta Mail if your mail service is already one of those privacy-first providers.

Thunderbird deserves the strongest recommendation because it handles IMAP and POP3 well, works with multiple accounts, supports calendars and contacts through add-ons or ecosystem tools, and is familiar to many users who are moving from Windows. On an LXLE machine, that familiarity matters. It reduces support overhead and makes day-to-day use less fiddly. Geary is the better option when you want something simpler and cleaner, especially on a machine with limited RAM. Proton Mail and Tuta Mail should be treated as service-specific apps: they are not universal mail clients in the old-school sense, but if you use those ecosystems, the desktop apps are the most straightforward way to keep your workflow tidy.

Here is how I would install and configure the best options on LXLE.

1) Thunderbird

On LXLE, the easiest route is normally the Ubuntu repository:

sudo apt update
sudo apt install thunderbird

If you prefer a newer Flatpak build and your LXLE install already has Flatpak set up, that is also an option. For a lightweight machine, however, the native package is usually the cleaner choice.

Configuration is straightforward:

• Open Thunderbird from the menu.
• Choose to add an existing email account.
• Enter your name, email address, and password.
• Let Thunderbird auto-detect IMAP and SMTP settings where possible.
• For providers like Gmail, Outlook, Fastmail, or Mailbox, use OAuth if the provider offers it otherwise use an app password where required.
• Set synchronisation preferences carefully if you are on older hardware: keep offline storage sensible rather than downloading every message attachment unnecessarily.

For LXLE, I would also suggest disabling unnecessary add-ons and keeping the message list clean. Thunderbird can do a lot, but on a modest machine, restraint keeps it snappy.

2) Geary

Geary is often best installed as a Flatpak on LXLE because that keeps the system package layer tidy and gives you a current version without depending on distro repositories.

flatpak install flathub org.gnome.Geary
flatpak run org.gnome.Geary

If Flatpak is not yet configured on your system, install and enable it first using your usual LXLE/Ubuntu package tools. Once Geary launches:

• Add your email account.
• Use IMAP for normal synchronised mail access.
• Allow automatic server detection, then verify incoming and outgoing server names if needed.
• Keep the folder view simple Geary is at its best when used as a straightforward inbox manager.

Geary suits people who mainly process email and want a clean interface without the weight of a full groupware suite. On LXLE, that often translates to better responsiveness and less clutter.

3) Proton Mail

If you use Proton Mail, the desktop app is a sensible choice, though remember it is designed for Proton accounts rather than general IMAP mail. For LXLE, the .deb package is the natural fit.

sudo apt install ./proton-mail.deb

After installation:

• Launch Proton Mail from the menu.
• Sign in with your Proton account credentials.
• Enable two-factor authentication on the account if you have not already done so.
• Adjust notifications and background sync according to how lightweight you want the system to remain.

On LXLE, Proton Mail is most attractive when privacy and account simplicity matter more than deep local mail integration. It is not trying to be a universal mailbox for every provider under the sun, and that is fine.

4) Tuta Mail

Tuta Mail is also a strong privacy-oriented choice and is available on Linux via AppImage or Flatpak. On LXLE, Flatpak is usually the more manageable route if already in place.

flatpak install flathub com.tutanota.Tutanota
flatpak run com.tutanota.Tutanota

Then:

• Log in with your Tuta account.
• Let the app complete initial sync.
• Review notification and startup settings so it does not consume more resources than needed.
• Keep in mind that Tuta is a secure ecosystem, so it is best used as intended rather than as a generic IMAP front-end.

Tuta is a particularly decent match for LXLE if you value privacy but still want a relatively neat graphical client. The AppImage route is handy too if you want to avoid system-level installation entirely.

As for the others on the list: Betterbird is a strong Thunderbird alternative, but I would choose it only if you specifically prefer its tweaks and do not mind the tarball-style distribution. Claws Mail is brilliant for low-resource systems and could be a top-tier choice for very old hardware, though its interface is more functional than friendly. Mailspring is attractive, but I would still steer LXLE users toward Thunderbird or Geary first.

Finally, if you are using a third-party email provider with LXLE, these are the ones I would consider most suitable:

• StartMail — a privacy-focused service that works well with desktop mail habits and suits users who want a more traditional email experience.
• Fastmail — excellent IMAP support, very reliable, and a particularly good match if you want Thunderbird or Geary to behave consistently.
• Proton Mail — best if you want strong privacy and are happy to live within the Proton ecosystem.
• Tuta Mail — another privacy-first choice, especially appealing if you prefer a dedicated encrypted mail app on Linux.

My practical recommendation for LXLE is simple: use Thunderbird if you need a proper general-purpose client, Geary if you want something lighter and more elegant, and Proton Mail or Tuta Mail if your chosen provider is one of those two. That combination respects LXLE’s lightweight nature while still giving you dependable email handling for everyday work.