[← All posts](https://xenrooms.com/blog/) · Published on 31 October 2026 · [Eugeny Syomochkin](https://xenaxio.com/about/)

# Slack Connect without Slack – chatting with other companies over Matrix

Email works between companies because every mail server speaks the same standard: your server sends, theirs receives, nobody needs an account with the other. Team chat has mostly not worked like that. Slack Connect links Slack workspaces, Microsoft Teams links Microsoft identities – each inside one vendor’s network. **Matrix** brings the email principle to chat.

## What Matrix is

Matrix is an open, documented standard for chat between servers. Every company can run its own Matrix server; servers exchange messages directly. This is called **federation**. Many apps and servers speak it – Element is the best known, XenRooms is another.

In XenRooms every company has a Matrix server of its own. Your chat address looks like `@anna:firma.xenrooms.app` – the part after the colon is your company’s server, the same way the part after the @ is the domain in an email address.

## How a shared channel works

1. Someone in your team creates a channel or a direct message and invites a person from another company by their Matrix address.
2. The other person’s server receives the invitation; they accept it in their own app – XenRooms, Element or another Matrix app.
3. From then on, both servers keep a copy of the channel and send each other new messages.

Nobody needs an account with the other company. In XenRooms a shared channel is marked **“External”**, and people from outside are marked **“Other company”** with their domain, so nobody posts something internal by mistake.

## What your administrator decides

Federation is powerful, so it needs a switch. In XenRooms the administrator chooses one of three settings:

- **Internal only** – no chat with other companies at all.
- **Xenaxio companies and a list** (the default) – companies on Xenaxio and XenRooms plus the servers the administrator adds.
- **All Matrix servers.**

Invitations from outside are never accepted automatically, and unwanted senders can be reported and blocked. New XenRooms Free companies can chat with other companies after seven days – a simple protection against spam.

## Where shared messages live

Say it plainly: messages in a channel shared with another company are stored on your server **and** on theirs – exactly like an email you send. Their rules apply on their server. Everything not shared stays on your company’s server only.

## Matrix and encryption

Matrix supports end-to-end encryption, and Element turns it on by default. XenRooms works like Slack instead: no end-to-end encryption, so search, the AI summary and the administrator’s control work; messages still travel encrypted (TLS). Both still talk to each other in unencrypted rooms.

## Why an open standard matters

- **Partners choose their own tool.** They do not have to join your vendor.
- **No lock-in.** If you change provider, the protocol stays the same.
- **Your server, your rules.** The administrator sets who can reach your team.

Want to try it? [Start XenRooms for free](https://xenrooms.app/en/start/) and invite a partner, or read more about [chat with other companies](https://xenrooms.com/features/external-chat/) and [what Matrix is](https://xenrooms.com/matrix/).

## Your team chat on a server of its own?

Free for up to 10 people, in a minute. For larger teams or your own servers we set up XenRooms for you.

[Start for free](https://xenrooms.app/en/start/) [Book a demo](https://essotec.xenaxio.com/book/es/first-call)

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Source: https://xenrooms.com/blog/chat-with-other-companies-matrix/ (English, updated 2026-10-31)
Other languages: Deutsch: https://xenrooms.com/de/blog/chat-mit-anderen-firmen-matrix/index.html.md