Penguin Mail – open-source Rust email client for Linux with AI | Hacker News Reader

Penguin Mail – open-source Rust email client for Linux with AI

penguin-mail.com

94 pointskavourias53 comments

That's a very nice looking app - I like the look of it it gives me Mail.app vibes.

A mail client is always a tough thing to get right so I'm glad you're working on one

I love then idea that as the total cost (time/money/attention) of personalizing software continues to come down, more people will be able to encourage a diaspora of options, tailored to each niche.

Visually it resembles Mail.app, but if it’s going for a similar level of functionality I think modern GNOME’s hamburger-and-three-dots-buttons approach to menus is going to become a problem.

This is one of those types of app that really benefits from a proper menubar with several top-level menus so the user isn’t stuck spelunking submenu tunnels.

I really hope we’ll see a KDE counterpart (and not in Kirigami; a proper one).

The industry standard wording is to suffix the headline with "written in Rust".

Example:

"Penguin Mail – open-source email client for Linux with AI, written in Rust".

Its important, or people might miss the most interesting/important thing about your software.

https://m.youtube.com/watch?v=qmVnr7rsWrE&pp=0gcJCY8Co7VqN5t...

Interesting that they call out Fastmail as a supported provider, but don't support JMAP. Seems like that would have been an easy stretch goal for Claude, and a good way to stand out amongst the competition.

not to mention jmap is a breeze to use

On the other hand, we focus _only_ on JMAP. https://www.ariamailclient.com

I wouldn't say it's something that can be vibecoded in a month or two. Proper design and implementation take time if you want to handle accounts with hundreds of thousands of messages seamlessly.

More importantly, which language(s) and UI toolkit are you using for your Linux app?

Does anyone remember Sparrow?

I like the idea of a native Linux email client. The UI looks pretty good too. It's really not hard to beat thunderbird.

Calling it version 1.0 is bullshit though. It's only about a month old: https://github.com/c9dev/penguin-mail/graphs/contributors?al...

A project with the complexity of an email client cannot be considered stable in a month. There are bugs that will only show up after a year. It has a calendar after all.

1. Being released on GitHub for a month does not mean it’s a month old.

2. Seems odd to assume instability by default without evidence.

Have you ever experienced stable-by-default?

If so, I'd love to hear a writeup!

Well, I'm trying it out and it seems stable.

It's missing some features that are dealbreakers for me, but I haven't found anything unstable yet.

So it's probably missing features which should make a good 1.0 mailer.

> The UI looks pretty good too. It's really not hard to beat thunderbird.

I don't understand this mentality. It's an email client. There's not a lot needed UI-wise to make a functioning interface. Display a list of emails, show the full message when you open it, etc. I don't see anything functionally different between this email app and basically every other one I've ever used.

You've either got insane standards or are using email way different than I.

Thunderbird still doesn't have proper threading

From an engineering standpoint, I get it.

But from a normal user's standpoint? I don't care. If my email client needs more than a single thread, something's fucked.

I randomly bounce between Thunderbird and KMail and honestly I can't tell the difference except cosmetically. Both are snappy. Neither crash. Both send and receive emails just fine.

Threading as in grouping together all replies to an email. This is still somewhat buggy on Thunderbird in 2026.

I know parent is probably talking about a different type of threading, but Thunderbird's lack of process threading means the UI just gets stuck when it's syncing a large numbers of emails, which can happen if your subscribed to a lot of mailing lists, etc.

Can’t speak for others but for me Thunderbird’s UI feels distracting and almost grating in some ways. It’s technically functional but doesn’t feel right.

I know things like that don’t bother some folks and that’s fine, but others like myself can’t turn the visual parts of their brains off and so some software feels like nails on a chalkboard to use.

The search is also incredibly slow. I didn't notice just how slow and inaccurate it is until I built my mail client on notmuch.

Clearly you have never tried to use Thunderbird...!

Does building in KMP count ? Check out https://www.ariamailclient.com

> Calling it version 1.0 is bullshit though.

There is a case to be made to always start at 1.0, especially libraries with public API’s. The reason is that if you use semantic versioning then below 1.0 you can’t properly declare a new release to be a feature or bugfix release (for example, 0.4 to 0.5. Is this bugfix or feature?). Above 1.0.0 this is easy (for example 1.1.0 vs 1.0.1).

In libraries, 0.x is for when you’re still figuring the API out. Basically you’re saying that no API is stable at this point, and you’re not doing semver yet, and anything can change.

Naturally, the users should treat those libraries as beta versions and only use them in production at their own risk.

> you can’t properly declare a new release to be a feature or bugfix

0.5.0 vs 0.4.1?

Is it perhaps because of the application speed in Rust?

I was wondering what “with AI” means and the page doesn’t really answer that thought the README does. It drafts replies.

Also it is made by pivotd ? What is it ? What is the end game ?

Genuinely curious as I am in the mail space with klar.im

Tested on fastmail, here’s few notes from 10min impression:

- can’t choose a sender email?! This is major dealbreaker, if you have many aliases or domains.

- no favico for emails, this is also a deal breaker for me, as I used it to quickly skim and find or check new emails.

- folders orders is messed up, trying to arrange them made it worse

- trying to color a folder and it says “server doesn’t support that”

Also the UI needs more polishing overall.

Thank you for testing on Fastmail for us.

I'll stick with the web UI in that case. Are you using any other clients on Mac or Linux?

I am using their official linux client, which is basically the web one in app form with notifications.

> - can’t choose a sender email?! This is major dealbreaker, if you have many aliases or domains.

Ugh, this drives me nuts. It's the same reason why I stopped using my Supernote Nomad for email.

I use iCloud+ email with a custom domain. With that arrangement you authenticate to Apple's servers with your iCloud "primary address", like someone.somename@icloud.com. Then you can send and receive email with your custom domain email address, which is the one you're actually using. But not with Supernote, or apparently Penguin Mail. My Nomad will only send mail with my @icloud.com address, even though that's only used for authentication.

So yeah, I just stopped using it altogether. That's not my address. It's not how people reach me. It's literally just a username.

This is interesting, I am doing an experimental effort with similar goals. What is your approach to testing? The bug surface of something like this is quite large. Also, do you have a plan for sandboxing?

Sandboxing should be handled externally by something like Flatpak

I was 100% interested until crossing "...with AI".

Same here. While I'd rather not have an embedded AI chat window, is there a way to disable it?

The homepage says “off by default”

Then my 'amail' client seems to fit the bill.. (OSS, rust, I use it on Linux and haven't tested elsewhere) ..not really suggesting it – it's pretty barebones and just whatever I've needed, but you're welcome to it obviously! Especially if you have issues/PRs to spur me on to features I've wanted too...

If you took the time to read, it is an optional feature and uses local models.

I would love an email client that automatically sorts my mails via a local LLM.

As long as it tries to be the "I" in "AI" and do something useful like automatically detect conversations with my accountant, per project and not per sender mails including somehow labeling mails referring to multiple projects with multiple labels etc.

Not that I think this mail client can do that...

Second that. I can’t really think of a better application for LLMs than this. In fact, this might be the only good application.

Drafting emails with LLMs is... ugh.

And assistant chat? Really?

Okay, two things might be great: translations (preferably local, e.g. using Project Bergamot) and message summary (in case somebody does send an unedited blob of LLM slop to me and social dynamics don’t let me send it to spam).

Surprised to see a new (large) GTK app, especially in Rust.

Can this be compiled for other operating systems than Linux?

It's vibecoded - new, large codebases are par for the course.

(This used to come at the cost of code quality, but increasingly does not.)

Got this building on FreeBSD for those interested:

1. Install the GTK stack:

  pkg install gtk4 libadwaita webkit2-gtk_60 pkgconf

2. FreeBSD ships WebKitGTK 2.46.6 and the project turns on the v2_50 feature of the webkit6 crate, so switch that to v2_46:

  sed -i '' 's/v2_50/v2_46/' $(git grep -l v2_50 -- '*Cargo.toml')

After that, cargo build completes against 2.46.

Is there anything like this but in TUI?

Not visually similar to the app discussed here, but some TUI options:

https://terminaltrove.com/herald/

https://terminaltrove.com/matcha/

And this is the one I use with Gmail, Outlook, Yandex:

https://terminaltrove.com/aerc/

https://terminalemail.com/

Maybe I'm not the target here but an embedded chat ai window is a huge turn off to me. Having a CLI I can give my own agent to access/query the data, if I choose to do that, would have been preferred but if the target was my mother, then a chat window is probably a better option.

I think this looks good, but I'm not on a Mac anymore.

For people that want a terminal client with tabs, integrated html viewer(including images), markdown compose, MCP, with unified inbox, I built notmutt.

https://fishman.github.io/notmutt/

I’m confused, is this a joke about how real Linux users only use console, or did you miss tbe part where it says it’s for Linux?

Yet another GTK4/libadwaita, no thank you. I mean, if you're going to use Rust and vibe code thing, why not use a more sensible, Rust-native UI like egui?

Went to watch the Youtube intro [1] for Penguin Mail and was greeted by the most egregious scam video. Didn't click the ad, but simply went to the domain (usbest1.com) and it's just chock full of AI generated content hoping to scam you out of your money. Going through the checkout flow, it even asks you if you want to tip your driver (presumably for delivery).

Sorry for the off-topic, but Google (and all ad networks) should be legally required to vet their advertisers. That's gotta be the worst I've seen.

[1]: https://www.youtube.com/watch?v=0PyJCsw1FSE

YouTube has some seriously scammy ads. To an extent that these ads have motivated me to buy premium for my parents as they tend to fall into the trap of fake dialog boxes shown in ads warning a PDF app needing an update.

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