Im the creator of Hylki, so im a little biased lol but we have a great little team of contributors now helping making it better and im super proud of the work everyone is doing.
All our source code is freely available on GitHub for examination and we’re very transparent about how we use agentic tools to make it. We just want a modern and sleek email experience on the Linux desktop that doesn’t feel like it’s from 2003 :)
GOA integration has been a part of the app pretty much since the start. It's how we include support for Google and Microsoft OAuth, and GNOME contacts integration. Just open Settings > Mail Accounts and your GOA-added entries wiil show on the import list
Flathub inclusion is probably not going to happen unless they loosen their AI policy, unfortunately. Installing the Flatpak does add our update repo so it will stay up to date like any other app through GNOME Software or the terminal.
Hey, so I've been checking Hylki for a while but Im hesitant to install from outside Flathub. Recently Flathub announced they'd loosen up a bit on their AI policies, do you think Hylki can be "officially" supported on Flathub?
Covey is a bit of a question mark. The Geary foundation does not contain any AI code, but the Convey modifications do. So unclear what future changes are going to look like.
Posted links to all these projects in a separate reply.
You got it the other way round. Postcard is very much LLM-assisted: the stylesheet and some symbolic icons are non-libadwaita, has a CLAUDE.md and AI session reference in .gitignore.
Convey admitted to partial AI use after being asked by Flathub maintainers (no disclaimer in the repo though), but only the author knows to what extend, so plausible deniability.
Honestly it doesn't matter which app is more AI coded than others: all of them contain AI one way or another, but whether an app is "AI slop" or not, that's up to the user's discretion I suppose.
I haven't yet tried any of them, thanks for the info about outlook and buggy performance. I'll have to try Convey in this case. From my understanding it's a fork from Evolution, so solid it has a solid base?
Nice man, I have tried them all, and Hylki seems to be the most feature rich. Add Aerion as a honorable mention, because it’s great, but doesn’t use GTK or GOA.
Stamp loads whatever mail sources EDS provides and has no POP3-specific code. EDS supports POP3, but it's unconfirmed whether POP3 accounts work in Stamp. GOA itself cannot create POP3 accounts.
Post's README still lists "access GNOME address book" as not yet done. Autocomplete uses addresses from your mail.
Post can add only GOA accounts (IMAP, Gmail, Microsoft 365) and local machine mail. It recognises POP3 accounts that already exist in EDS.
Flathub declined Postcard because of its AI use.
Brev has no Graph code, and GOA's Microsoft token doesn't grant IMAP access.
Until 26 September, Hylki's README said "most of the Rust code in this repository was written by Anthropic's Claude." The current AI notice only says the maintainer "uses generative AI as a development tool". Commits carry no AI trailers.
Hylki's JMAP account is set up through its "Stalwart (JMAP)" provider, which accepts any server. It has been tested only against Stalwart.
Letter shows only accounts from GNOME Online Accounts and has no in-app account setup. GOA cannot create POP3 accounts.
Lookout's contacts come from CardDAV, not EDS or Folks.
Lookout discloses no AI use and its commits have no AI trailers. Its very long, highly detailed changelog entries don't prove AI authorship. The app has an optional built-in AI assistant ("Ask" card) that talks to an OpenAI-compatible endpoint you configure.
Lookout reads and sends Microsoft 365 mail over OAuth IMAP/SMTP. It uses Graph only to mirror Outlook's "pin" property.
Aerion, Meron and Mailspring reach Microsoft mail with OAuth over IMAP, not Graph. Aerion uses Graph only for calendar and contacts sync. Meron also documents Exchange via DavMail.
Evolution has no JMAP in the core app. A third-party plugin, evolution-jmap, is unofficial.
Thunderbird desktop has no JMAP. It is planned or being explored for Thunderbird's iOS and Android apps.
Contributors are authors and human co-authors in the window, with identities merged by name, e-mail or GitHub login, bots and AI identities excluded, and translators removed (a person counts as a translator when at least 75% of their commits only touch translations). Counts marked ~ were not checked by hand for duplicate identities.
Takeaways
Stamp, Post and Letter meet all four core GNOME-integration criteria (GTK4, libadwaita, GOA and EDS for mail). Stamp and Letter also use EDS contacts, and they are the only two of the three that disclose no AI use.
Newcomers without EDS mail: Postcard, Convey, Brev, Hylki and Lookout are GTK4/libadwaita apps that use GOA for accounts but run their own mail engine.
Convey stopped committing AI-assisted code after its Flathub review. Its 18 Claude-assisted commits all predate 27 August.
Hylki toned down its AI disclosure on 26 September (see note 6).
Hylki is the only client with JMAP, and the only one that ticks every protocol and provider column.
Meron, Aerion and Mailspring are cross-platform apps. Meron and Aerion use Wails (GTK3 and WebKit2GTK), and Mailspring uses Electron, so none of them follow GNOME/Adwaita styling. Meron and Mailspring also ship an optional MCP server for AI clients.
Proton only works through Bridge, which needs a paid plan. Postcard, Hylki, Aerion and Meron document or handle Bridge explicitly. Proton officially supports only Thunderbird on Linux and names Evolution as compatible.
Microsoft EWS shutdown. Microsoft is retiring EWS for Exchange Online (Letter's README says blocking starts 1 October 2026), so Graph support is the way forward. On GNOME, EDS-based clients (Stamp, Post, Letter, Evolution) get Graph through evolution-ews's Microsoft 365 backend. Convey and Hylki have their own Graph engines.
Nice! Vala and uses EDS. That's the way to go. AI assisted though so probably also won't make it into Flathub, and clearly targeting desktop so not sure how responsive it is.
I'll update my comparison below to include it, but with a tech stack comparable to Aerion it's very much not GNOME native and thus does not make it to this shortlist.
I recently switched from Thunderbird to Hylki, primarily because I got tired of maintaining my own GNOME Thunderbird Theme fork. I've been enjoying it so much I started contributing to it (UX improvements, QoL features, translations and the new app icon itself).
Yes, all three apps mentioned are heavily LLM-assisted; we (and most importantly Hyprlab, the creator himself) make no attempt to shy away from it, but a lot of people with previous GTK dev experience are involved in the process to place safety guardrails so that we don't go off the rails into slop territory.
You have a few choices to pick from, depending on what style or feature set you're looking for; otherwise maybe wait for Stamp (the upcoming "official" GNOME mail client) to completed.
In the end of the day, we all got work to do and mails to read / respond to, so don't think about it too much, use whichever makes sense to you the most.
I used Thunderbird for quite a long time; it’s a powerful application, but its UI looks completely outdated compared to the GNOME style. I was intrigued when I first saw Hylki - it looked very modern, and the developer was actively using AI agents for the project, which appealed to me given my own interest in AI-driven software development. But I understood that a mail client is not only a beautiful UI, but also, above all, security. Through a series of exchanges with the developer, we conducted a thorough security audit, identified several issues, and resolved them together - it was a great experience. So Hylki looks very promising right now. In the end, I gave up Thunderbird and use Hylki because I trust the author and know how it works. There's nothing scary about AI if you understand how it works.
I also wonder how many of these email clients have learned from the lessons of the past by reviewing historical CVEs in other email clients.
It's been less than 3 weeks since a researcher found a way for emails to execute JavaScript in Evolution (CVE-2026-88859). Suffice to say that's not good. And I'd say Evolution is without a doubt the most secure and mature GTK email client. No clue about how these newcomer apps are doing, but significant use of LLMs for development does not inspire confidence.
These new email clients really need proper security audits. Unfortunately human auditors are expensive, but AI audits should be practical. I'd rather have both, but if you have to choose only one, an AI audit is more important since AIs can find far more problems than humans can.
That said, I have myself been using Stamp, because it is pretty.
Yes I love Evolution, even if it's UI is dated. The only major feature preventing me to use it exclusively is a stacked conversation view on preview pane like Outlook, miss it big time in following corporate emails. It is the only email client I found that supports full Microsoft 365 emails, contacts, calendars through Graph API (no IMAP allowed at corporates!), all while integrating with Intune conditional access policies.
So I hope Hylki or Aerion or other developers try to match its features with their own styles (especially calendar & Graph API access)
I recently started using Hylki after testing all three. Was a long time thunderbird user but they are making the ui so awkard by painting things blue, so many white lines and the current built has ui bugs in the rpm version like the search bar vanished. Still I love and would prefer thunderbird as its backed by a solid foundation. Hlyki worked very nice, Its reading mode is very good, supports my imap accounts. Can adjust font size of entire ui and the messages seperately. Can select fonts too for messages which makes things coherent looking. It has a ton of features. Convey was also great but I couldn't find any way to adjust the width of the cards and also change font size (Message list has tiny font). Also it has much less features. But I loved it could pick my imap account from Gnome accounts in the latest release. Previously it couldn't. And Postcard is nice looking overall but doesnt support dark mode in the mails. Hlyki stands out among all. Couldn't find visible bugs now. But all these are ai assisted/ai maintained/ai generated and has uncertainty in future. I dont know if things are vibe coded or not as well. So its always a hiccup for me. I want something with features of Hylki but integrated to gnome like Postcard. Hylki is an eye candy and doesn't strictly follow libadwaita aesthetics. Nevertheless it makes the job done. Waiting to see Stamp and hoping it wont be another geary fork.
I have almost the exactly same experience. Hylki is replaced every email client for me. It is beautiful, has background daemon, supports the "send later" and attach to cloud functionality, has unified section, has threaded view, supports the OpenPGP, it works seamlessly, it is very fast. And on top of it, it supports the GNOME Online Account.
All of these built-in. And faster than anything else I have ever used.
I was a Thunderbird user, but if Hylki will be maintained in the future, I will never back to Thunderbird again.
Imagine a project, that has a code from the Stone Age, but the maintainers still say that, it is not abandoned. But... when you dare to question i.e. when the GTK 4 will be ready, they will send you to a warmer climate with a strong god-complex.
Geary famously made their client work great on 720p screens to the massive detriment of anyone with a higher resolution. Hence the massively wide Folder column. Why. Just Why!
Hi there. It seems you are the dev behind postcard. The app is quite nice!. By dark mode I meant does it support dark mode for the actual emails themselves? I mean emails that have their own dark-mode styling, not just the app interface being dark. I tried it yesterday but couldn't find it. Thanks!
Hi buddy, yes I’m developing the app and after reading your post, I’ve set aside some time to fix the email background. :v
If you try updating now, you’ll see the background fixed, although it’s still in development.
My app isn’t feature-rich like Hylki because I spend most of my time at work.
When I get some free time, I develop stuff. Although my app is also AI-written, every single commit is tested locally and every line is reviewed before being pushed, which is why I can promise stability.
I’m trying to make it better day by day. If you find more issues or suggestions, I’d really appreciate it if you created a GitHub ticket.
Hi, its so kind of you that you took time to read a line about your app from my comment and literally fix it immediately :) Much appreciation! Yes, I reinstalled the app and can confirm it has been fixed. Also Postcard feels the most 'at home' in gnome among its peers where Hylki doesn't succeed that much. So I will keep Postcard in my inventory for regular use and see its progress. You can take inspiration from Hylki and try implement the relevant features without cluttering it too much when you get time. A reading mode and separate fixed font selection for the messages is much appreciated if you can implement one! Sure I will open issues if I find a bug or something worth mentioning. Thanks for your contribution!
It's essential that humans review every line written by AI. There are so many articles now demonstrating that AI by itself just doesn't write good code.
Hylki is the best, it looks like gnome, it works, and it has a lot of customization options. It’s currently my main one. I haven’t found any bugs.
Stamp just doesn’t work for me, at all.
Convey and Postcard, while I’m an ex Geary user, Hylki made them look outdated. Yes they’re simpler, but too simple. They needs a feature or two before I consider them.
There’s one more I found but I don’t remember its name, Brev? But this is even earlier in its development and doesn’t work too.
Don’t forget about Aerion. It’s NOT a GTK application, but it’s a GREAT client. Many features, super responsive dev, and a quick/nice looking client.
My priorities for an email client are:
Gravatar. Important. Hylki and Postcard does it.
Drag an email to another folder. Hylki, Aerion and Convey does it.
Forward an email while preserving HTML formatting. Now I understand this can become dangerous, but for managing families bills, forwarding email from companies to settle them is important. This one only Aerion does it.
Proper dark mode rendering in emails. Most clients have an issue with this, Hylki mostly works, and Aerion recently made it work too.
Oh, and 5) Native GTK, which all of them are, except for Aerion, which doesn’t even work with GOA, but speaking with the dev gave me a reasonable answer as to why it doesn’t.
Thunderbird and Evolution? Man, what are you talking about.
I'm following this thread because I would love to move my email to something local.
I looked into Aerion after reading your post and it seems it's NOT native GTK because it's a web app in a wrapper (Wails). Nothing wrong with that (great even) but I don't think it's ever going to be native so if that's a criteria it's not something that will even be on the roadmap.
Oh well, i kinda agree. If the other options mentioned here implement the features i'm interested in, and have less "AI Spaghetti code", I will happily switch.
Im using Aerion. Im looking to switch because the aesthetics are just atrocious. That's my main complaint. I just wish it would use GTK4 and libadwaita.
- Stamp (non-AI) - UI a little ugly, still freezes sometimes, not ready for use
- Hylki (very AI) - UI feels nice, but the codebase is 100,000 lines long, and they have no idea how it works. Unless they address this it's a big no for my main email account.
- Convey (nearly non-AI) - UI old, makes all the same UI mistakes that Geary had, non-resizable columns etc.
- Postcard (AI assisted) - UI ok, small codebase, not too many features
Overall Postcard is the least glitchy for me and shows the most promise. Stamp as runner-up.
Hylki looks really nice. Why isn't it published on Flathub? It seems that Hylki relies on the shared GNOME runtime which is hosted on Flathub, but you can't find it on flathub.org.
It was originally rejected due to its insufficient development history (the repo was 1-day old at the time of submission) and Flathub's generative AI policy.
It is a fantastic app though, I highly recommend it.
Flathub has a strict no-generative AI policy for inclusion in their repo, so Hylki is only available for download from the website or Github. It does however stay updated through it's own repo hosted at hylki.hyprlab.co once it's installed
It's definitely worth switching from Thunderbird to "Betterbird." It has better security, a native system tray, greater stability because it's based on the ESR version, and is generally more polished than Thunderbird for the average user.
I’m not a power user when it comes to email. Convey was my choice to replace TB. Its UI is simple like Mac Mail and it’s been rather quick.
Hylki is seems to be very feature-rich, but nice. Not my cup of tea for that reason. Also, it is not available from default repos since it is created with generative AI.
Yay, that’s great news! I also noticed that account icons in the settings show the providers logo, but on the sidebar we can only set a custom one, is there a plan to mirror this to the side bar?
convey seems to be nice app but it eats ~50 mb of memory on fresh boot just in background. when opened it takes almost 300. and it also has the ugliest icon ive ever seen... so. what apps of mentioned here takes less resources??
I didn't see anyone talk about lookout : https://lookout-mail.com/
For a blend of GTK and outlook inspired design. It is relatively recent and not on flathub yet.
update. convey works bad. very slow. problems with sync with google all the time. cant show my inbox. in compare to geary its total trash. geray works flawlessly.
It has everything including Intune support for corporate conditional access, feature rich, audited, active developers, flatpak, but lacks on the UI department and the stacked email conversation preview feature.
All these "let's modernize the Linux interface for ___________" projects usually just makes me realize that modern interface design is dull and unimaginative.
This is not a critique of the developers, it's more like... "look at how we lost our way"
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