Meet Hylki: The Rust-Powered GNOME Email Client Built with LLM Assistance

The Linux desktop ecosystem has long experienced a revolving door of email clients, particularly within the GNOME sphere where users continually search for modern, user-friendly alternatives to fill the void left by the stagnation of classic applications like Geary. Into this evolving landscape steps a new contender: Hylki. Developed in Rust and tailored specifically for the GNOME desktop environment, Hylki presents a sleek, modern GTK4 and libadwaita interface structured around a familiar three-column vertical layout.

Originally known under the moniker Vireo—a name that had to be abandoned following a naming conflict with a macOS developer—Hylki joins a fresh wave of modern Linux mail clients that includes projects like Postcard, Convey, and Letters. These applications share a common goal of providing streamlined, lightweight, and visually cohesive communication tools for users who prefer native desktop integration over webmail interfaces or heavy Electron-based wrappers.

Promising to be fast to open, effortless to read, and private by default, Hylki enters a crowded field aiming to capture the attention of GNOME enthusiasts. Behind its contemporary exterior and polished ergonomics, however, lies an unconventional development story that touches on modern software engineering practices, artificial intelligence, and the subtle quirks that can arise when code is generated with the help of machine learning models.

Core Features and Ecosystem Integration

Under the hood, Hylki is designed to integrate seamlessly into a user’s existing workflow. The application can connect to any email account configured via GNOME Online Accounts, while also supporting manual POP3 and IMAP configuration for users who prefer direct setup. Multiple accounts are fully supported, allowing users to browse individual inboxes separately or aggregate everything into a unified inbox view.

Following the standards set by modern webmail providers and legacy clients like Geary, Hylki utilizes conversation threading, grouping related messages together into a single, cohesive view to reduce clutter. When composing messages, users have the flexibility to write inline or launch a dedicated pop-out window. The composer supports various formats, including rich text, Markdown, HTML, and plain text. Furthermore, the client includes a convenient "send later" queuing system, alongside OpenPGP integration via host packages to allow users to read, sign, and encrypt their communications securely.

Beyond standard email management, Hylki incorporates several novel features aimed at improving the reading and organization experience. A dedicated "reader mode" strips away distracting graphical elements, reducing mail content down to clean, readable text. The application also includes a built-in selection of themes and alternative icons, deep integration with GNOME Contacts, and a "focus mode" designed to hide toolbars and other management clutter out of view.

Comfort features abound within the interface. Hylki supports Gmail-style single-key shortcuts, a background application mode for continuous synchronization, gesture support for touchpads or touchscreens, and the ability to run the application in a language different from the system default. Users can take advantage of one-click unsubscription from newsletters and view automatically rendered thumbnails for attachments.

Customization is another area where the client shines. Settings allow users to configure the number of lines displayed in inline message previews, rearrange the order of buttons in the toolbar, and create local mail filters to automatically sort incoming correspondence.

Developed with LLM Direction

Perhaps the most talked-about aspect of Hylki’s development is its reliance on artificial intelligence. The application’s developer has candidly stated that Anthropic’s Claude was used to write the majority of the underlying code. However, this was not a completely hands-off automated process; the AI operated strictly under human direction, and every single output was meticulously reviewed and tested by a human maintainer who ultimately signed off on every release.

It is worth noting that the application itself does not incorporate any AI features, whether local or cloud-based. This architectural decision ensures that there is no direct risk of important emails or entire inboxes being compromised by an over-enthusiastic LLM misinterpreting data. Nevertheless, anxieties regarding machine-generated quirks remain a talking point among privacy-conscious Linux users.

Interestingly, while the code was generated with AI assistance, all visual artwork in Hylki—whose name derives from an Icelandic word meaning "capsule"—is entirely human-made. The main application icon and brand logo were crafted by designer Yiannis Ioannides.

When evaluating software built with the help of artificial intelligence, different members of the open-source community draw red lines in varied places. While some focus on philosophical objections, others judge the software strictly on its execution and usability. In practice, Hylki looks visually appealing and functions smoothly, though it occasionally betrays its artificial origins to observant users. There is a subtle, almost psychological sensation that something is slightly unusual about the user interface of LLM-assisted GTK applications—a peculiar juxtaposition where certain minor details lack polish while other elements receive an unexpected surplus of attention.

Installation and Availability

For users wishing to test out Hylki, the application is distributed via a custom Flatpak package. While it cannot be installed directly from traditional repository managers in the standard fashion, it requires Flathub to be enabled on the host system because it relies on the shared GNOME runtime installed by other compliant applications.

Users can add the Flathub remote if it is not already present and then install the application using command-line instructions provided by the project. Because the application is distributed outside standard centralized repositories like Flathub itself, future updates must be downloaded and reinstalled manually rather than updating automatically through a standard software center.

Whether Hylki ultimately proves superior to alternatives like Postcard or Convey, or if it can successfully unseat more established heavyweights, remains entirely subjective. Many users still prefer to keep a dedicated desktop client around specifically for secondary email accounts or offline management. While Hylki shows immense promise with its modern design and thoughtful feature set, options like Thunderbird continue to command a strong following for general daily use.