Chatmail - replicable, fast and secure chatting infrastructure for all

December 13, 2023 by holga, nami, x, l, bjoern

Today, we are unveiling chatmail services, making onboarding with Delta Chat a breeze, with peace of mind:

Chatmail logo

Too good to be true?

Try it out

You may peek at, and after installation of a Delta Chat app, simply tap or scan the below QR code to get a address

After setting your avatar and name, message and observe a (rapid) reply.

Please let us know about success and especially failure to help us streamline, the first public chatmail service which we aim to keep running as a community service.

How to make e-mail spammers sad, and users safe currently allows to send 60 messages per minute for any user and you can register multiple e-mail addresses. Isn’t this paradise for abusers wanting to send out lots of unsolicited messages? Wouldn’t this get chatmail services insta-blocked from other e-mail providers?

Fortunately, there is a simple twist to prevent account abuse: A chatmail service doesn’t allow to send un-encrypted messages to anyone outside the service. This makes spammers sad who would try to abuse open-signup chatmail addresses because they first would need to setup OpenPGP encryption with all recipients, a known hard problem and thus a substantial proof of work, no? :)

More seriously, Delta Chat uses the decentralized Autocrypt standard which does not publish or centralize encryption keys anywhere. Moreover, today’s Internet platforms track everything except OpenPGP keys and so can only sell or leak to spammers profiled e-mail addresses but not encryption keys. It’s therefore a massive uphill struggle and economically un-interesting to abuse chatmail accounts for mass-sending unsolicited mail.

For when this economic constraint changes, we may have some aces up our sleeves to make spammers and surveillance actors even more unhappy. But more about that when the time comes.

Use guaranteed end-to-end encryption to reach any e-mail address

We generally recommend to use QR-code scans to setup guaranteed end-to-end encryption with other chatmail or e-mail users. This way, you can safely chat no matter what chatmail or e-mail server contacts use. Setting up guaranteed end-to-end encryption minimizes the trust you need to have in chatmail or traditional e-mail server operators. Chatmail operators generally can’t read the content of messages and by design hardly know any personally identifiable data.

Chatmail services really act more as an e-mail router rather than an account platform. Anyone can get a slot but only end-to-end encrypted messages can freely travel.

Registering with newsletters or platforms, without privacy leaks

Delta Chat apps supports using multiple addresses out of the box. With you can always setup additional addresses to receive newsletters or register with websites. Incoming messages are allowed to be un-encrypted (this might become user-configurable in the future) and so they are just fine for receiving e-mail messages.

If you don’t need or use an additional address anymore, simply delete it on your device. We are happy to see you go and, who knows, maybe re-enter with a new e-mail address, possibly using Tor or a VPN?
This way the chatmail-server never even sees your Internet address which is anyway only ephemerally logged and not collected. Speaking of not collecting data, please see nine’s state-of-the-art privacy policy which was created by the data protection specialists and our long-term supporters at
One of the german classics on “Data protection at the work place” was btw co-written by Fabian Schmieder, our appointed privacy officer of all mail services. and running chatmail services yourself

future of email screenshot on testrun banner

Our just published Chatmail repository contains the executable blue-print for setting up a modern e-mail service, of which is the first public instance. It is operated by some Delta Chat project members, on the side. This mirrors how we envision chatmail services to be operated: by a small group or individuals who don’t need to worry much or spend a lot of time on the service, but who enable reliable and secure chat communication for many thousands of users. We haven’t fully explored limits yet but nine has already served >100K accounts and millions of messages before now going public. Day-to-day development of the deltachat-core-rust library creates around 10 new accounts per commit and there are many commits per day. In other words, availability and reliability of is continuously verified, and it is maintained and refined through the public Chatmail repository.

With some knowledge of DNS, SSH and a spare VPS (get the cheapest you can find), you can setup and offer chatmail services yourself pretty quickly. A friend easily recently set it up on a Raspberry Pi for his housing project. Chatmail servers are designed to run with minimal hardware requirements and to be easy to tweak even from novice sysadmins or programmers. No permission is needed from our side to run a chatmail server. We might not even know you are doing it because Delta Chat has no tracking or counting.

But we warmly welcome feedback (especially bug/success reports!) and contributions via the Chatmail repository and also intend to do workshops and sessions at both the upcoming 37c3 Chaos Communication Congress end of the year in Hamburg, as well around OFFDEM/FOSDEM in Bruxelles beginning February 2024.

Wait a moment, sub-second delivery?

Yes, here are some benchmarks, run on a remote machine against, with a network latency of 20-30ms per internet data packet:

benchmark name                 median    min    max
dc_autoconfig_and_idle_ready     1.17   1.14   1.18
dc_ping_pong                     0.46   0.43   1.05
dc_send_10_receive_10            2.22   1.77   2.22

dc_ping_pong measures two end-to-end encrypted device-to-device message deliveries. One chat message is thus delivered end-to-end/device-to-device in a quarter of a second.

If you don’t believe that this screen-recording reflects the actual speed please verify it yourself, and scroll up to the beginning of the post :)

Why are we not making a bolder fuzz about probably launching the fastest e-mail service on the planet? The answer is twofold:

Yes, chatmail is blazing fast but that’s not a purpose in itself. Making secure, interoperable, decentralized, guaranteed end-to-end encrypted communications available for all, is more important than sub-second delivery. It is not another business model that can replace Whatsapp/Meta, at least not without becoming their mirror image. Only communities who sovereignly run their own infrastructures, evading centralized control and dependencies, might free themselves.

The e-mail network is a vast rhizomatic space which surrounds us already, and is diversely deployed at planetary scale. We hope many of you join the amusing journey in exploring it further :)

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