Why I Gave Desktop Email Clients Another Try and Found Aerion Wins Me Over

For anyone who deals with a high volume of email daily, a dedicated desktop client can be a game-changer. Instead of juggling multiple browser tabs for different accounts, these applications consolidate everything into one streamlined interface. They provide tools for composing, organizing, and syncing messages—all without the overhead of a web browser. I first cut my teeth on Thunderbird years ago at a former job, and it served me well. But over time, I migrated to web apps out of convenience. Then I stumbled across Aerion, an open-source, lightweight desktop email client, and decided to give the desktop approach another shot.

Meet Aerion: A Fresh Take on Desktop Email

Aerion is developed by a small team sponsored by 3DF, which covers infrastructure and staffing costs. It takes design cues from GNOME’s Geary but aims to be even more resource-efficient and clutter-free—a welcome change from the heavier Linux email clients. And before you groan at the mention of Electron, know that Aerion uses Wails and Svelte under the hood, keeping its footprint minimal.

Security That Matters

A noteworthy selling point is its CASA Tier 2 certification, assessed by TAC Security (a Google-authorized assessor under the App Defense Alliance). This means an independent third party scanned the codebase against OWASP ASVS standards. For a project handling email credentials, that third-party validation offers real peace of mind.

Features It Brings to the Table

Aerion covers the core functionality you'd expect:

• Support for multiple email accounts
• Conversation threading
• A WYSIWYG composer built on TipTap
• Contact sync via CardDAV, Google, and Microsoft
• Multiple color themes
• Keyboard navigation with vim-style shortcuts

For providers, it works with Gmail, Microsoft 365/Outlook, Proton Mail (through the paid Proton Bridge), iCloud Mail, GMX Mail, and generic IMAP/SMTP. Yahoo, Fastmail, Zoho Mail, AOL Mail, and Mail.com are listed but marked untested. Do keep in mind that Aerion is still pre-release, so occasional hiccups are possible.

My Hands-On Experience

Setting Up a Gmail Account

Adding my Gmail account was surprisingly smooth. Aerion redirected me to my browser for the OAuth flow, where I completed Google's standard permissions. A moment later, I was back in the app, authenticated and ready. However, there's a frustrating catch: if you accidentally click outside the Add Email Account window while it's open, the entire popup closes without warning or confirmation. Any progress is lost instantly—a harsh UX that needs addressing.

Fetching and Organizing Mail

Once set up, fetching mail proceeded reasonably fast. The interface remained responsive even while downloading messages from multiple folders. Conversation threading worked well, grouping related emails in a clean, readable tree. The WYSIWYG composer feels modern and responsive, though I miss a few advanced formatting options.

Performance on Low-End Hardware

I tested Aerion on a modest Linux laptop with 4 GB RAM. It idled at around 180 MB of memory—impressive for a modern email client. The app launched in under three seconds, and switching between accounts was near-instant. For comparison, Thunderbird on the same machine uses roughly 300 MB at idle.

Jump back to the features section to see what other options are available.

Should You Switch to Aerion?

If you value a lightweight, secure, and open-source desktop email client, Aerion is worth a serious look. It’s not yet feature-complete—some provider integration remains untested, and the window dismissal bug is annoying—but the core experience is solid and fast. For those who rely on keyboard shortcuts and a clean interface, it could become your daily driver. Keep an eye on its development; this little app has room to grow.