ArcaneChat is a Delta Chat client and uses the Delta Chat core (which contains all the crypto and logic and any app can use to implement e2ee IM) and it is based in the Delta Chat client, which has been audited around 6 times over the years: https://delta.chat/en/help#security-audits

For sure!! The app is decentralized/federated. You can host your own server: https://github.com/ArcaneChat/chatmail

And some 3rd party servers are discoverable inside the app at registration time.

The app can also be used with classic email servers so if you have an email server you can use it as well with ArcaneChat

If what you want is private/secure encrypted email that the provider itself can not even read, I recommend you arcanechat.me

no, there is no important metadata leaked via headers, the only obvious data the server knows is the same as on Matrix and XMPP, when you tell the server to deliver the message to a given user, the server hence knows that X sent a message to Y, but since accounts are randomly generated email addresses without any personal data tied, this is more secure than Signal where phone numbers are collected by a central server and if they wanted to they can match your IP to your phone number even if you use sealed sender to send it is obvious who you are by your IP and timing since you also connect to the server non-anonymously to receive messages

at the moment there is not “integrated calls” that would cause the phone to ring, but it is planed, but what is available is calls/video-calls invitations in-chat that show a nice “Foo invited you to a video call” message in chat with a button to join but on click it just open the call room in Jitsi Meet app or web browser

the app is much more on the WhatsApp and Telegram level UI wise, much more user friendly for “normies” like family and friends, while Matrix and XMPP are more “nerdy” and hard to understand and onboard

Nice multi-device (that actually works without encryption problems) and multi-account support.

Security-wise it is easy to end up sending unencrypted messages in XMPP (groups are often unencrypted due unusable otherwise) and in matrix it is also a mess with “unable to decrypt” and the reactions are not encrypted. ArcaneChat groups and 1:1 chats have a concept of “protected chats” via scanning QR or invite links that are warrantied to be e2e encrypted and safe against MITM attacks.

Groups in XMPP depend on the server, if the server dies the group is lost, in Matrix the groups metadata is spread across several servers, in ArcaneChat the servers are agnostic of the group state, the group lives in the users’s devices and hence don’t depend on any server, user can even migrate account/address and keep participating in the group

The server requirements for ArcaneChat are super lightweight (ex. https://arcanechat.me/ has +700 users right now and it is only using ~500MB of RAM and ~3GB of disk) in this regard XMPP might also be similarly lightweight but Matrix is well know for the complexity and requirements on the server

ArcaneChat is offline-first, you can fully use the app while being offline, even create groups, search across all your groups, messages and contacts, play in-chat mini-games or use collaborative tools like in-chat WYSIWYG editors etc. send messages etc. and all will be nicely synchronized when you go back online.

ArcaneChat is super lightweight, apk size in google play is only 13-15MB while being feature rich and beautiful

creating bots to provide extra functionality (similar to telegram bots) is easy and there are already several bots available and discoverable in the app.

Now lets talk about some downsides:

ArcaneChat doesn’t support integrated phone calls at the moment (but it is planned, and it has jitsi meet videocall invitation integration)

ArcaneChat doesn’t support discoverable public groups or channels (it is an app for private chats, you can invite people to group via invite links tho, and telegram-like channels are in the roadmap) a public bot can be used to list and join “public” groups tho, but at the moment everyone in the group is admin, there is no group admin concept as groups are private

there are more stuff to say but this post is too long already 😅