10 Essential Facts About the Aerion Desktop Email Client You Should Know

If you juggle multiple email accounts daily, you've probably relied on a desktop email client at some point. These applications consolidate all your inboxes into one interface, saving you from hopping between browser tabs. While many of us have gravitated toward web-based email over the years, a new contender called Aerion has emerged, promising a lightweight, secure, and open-source experience. Intrigued by its claims, I decided to give it a try after a long hiatus from dedicated email clients. Here are ten key things you need to know about Aerion, from its core features to its quirks.

1. What Is Aerion?

Aerion is an open-source, lightweight desktop email client primarily developed for Linux. It draws heavy inspiration from GNOME's Geary email client but aims to avoid the bloat that often plagues older solutions. Under the hood, Aerion uses Wails and Svelte—not Electron—which means it stays resource-efficient. The project is sponsored by 3DF, covering infrastructure and developer costs. Think of it as a modern, streamlined home for your emails that respects your system's memory.

2. Security Certification That Stands Out

One of Aerion's most reassuring aspects is its security. It holds a CASA Tier 2 certification, assessed by TAC Security, a Google-authorized evaluator under the App Defense Alliance. This means the entire codebase has been scanned against OWASP ASVS standards by an independent third party. For a small indie project handling your email credentials, this independent verification is a huge plus, giving you confidence that your account access is handled securely.

3. Supported Email Providers – A Broad but Cautious List

Aerion works with major providers including Gmail, Microsoft 365/Outlook, Proton Mail (via the paywalled Proton Bridge), iCloud Mail, and GMX Mail. It also supports generic IMAP/SMTP setups, making it flexible for custom domains. The client lists Yahoo, Fastmail, Zoho Mail, AOL Mail, and Mail.com, but these remain untested at the time of writing. So while the support is wide, you may want to stick to the confirmed providers for a smoother experience.

4. Core Features That Cover the Essentials

Despite its lightweight nature, Aerion packs the features you need. It supports multiple accounts, conversation threading, a WYSIWYG composer powered by TipTap, and contact sync via CardDAV, Google, and Microsoft. You can choose from multiple color themes and navigate through your inbox with vim-style keyboard shortcuts. These features make it a solid option for anyone who values efficiency and customization without the clutter of heavier clients.

5. Getting Started with Gmail – Surprisingly Smooth

Adding my Gmail account was refreshingly straightforward. Aerion redirects you to your browser for OAuth authentication, where you go through Google's standard permissions. Once authorized, you land back in Aerion fully authenticated. The entire process took less than a minute, and the app immediately began fetching emails. For a pre-release project, this level of polish is impressive.

6. A Frustrating UI Quirk to Watch Out For

However, Aerion isn't without its rough edges. When adding an account, if you accidentally click outside the "Add Email Account" window, the entire setup discards your progress—no warning, no confirmation popup. This can be incredibly irritating if you've already entered credentials. It's a small but sharp pain point that the developers will hopefully address in future releases.

7. Performance and Resource Efficiency

Unlike many modern apps built on Electron, Aerion uses Wails and Svelte, which compile to native code. The result is a client that stays nimble even when handling multiple accounts. During my testing, the app used significantly less memory than Thunderbird or web-based Gmail in a browser. For users on older hardware or those who prefer a lean system, Aerion's efficiency is a major selling point.

8. Customization Without Overwhelm

Aerion offers enough customization to suit your workflow without becoming overwhelming. You can switch between several built-in themes to match your desktop environment, and the vim-style keyboard shortcuts let power users navigate quickly. The TipTap composer is clean and intuitive. While it doesn't include advanced plugins or scripts, the available options cover what most people need from an email client.

9. How Aerion Compares to Traditional Clients

Compared to Thunderbird, Aerion feels more modern and less bloated. Thunderbird has decades of extensions and features, but Aerion focuses on a minimal, fast experience. It also differs from web apps by offering offline access (once fetched) and consolidated notifications. If you've been using browser-based email, Aerion provides a dedicated environment that can boost productivity—just be prepared for its pre-release limitations.

10. A Project with Promising Potential

Aerion is still in pre-release, so some bugs and missing features are expected. Yet the foundation is solid: open source, independently security-audited, and resource-efficient. The team is actively developing it, and the community shows interest. If you're a Linux user looking for a fresh email client that respects both your privacy and your system resources, Aerion is worth a try. Keep an eye on its progress—it might just become your daily driver.

In conclusion, Aerion proves that desktop email clients are far from dead. By combining a lightweight architecture with essential features and a security-first mindset, it carves out a niche for itself. Yes, there are a few rough edges (like that accidental click issue), but for an indie project, it delivers a surprisingly polished experience. If you've been relying solely on web-based email, give Aerion a shot—you might find it reinvigorates your workflow.