synapse/docs/server_notices.md

Server Notices

'Server Notices' are a new feature introduced in Synapse 0.30. They provide a channel whereby server administrators can send messages to users on the server.

They are used as part of communication of the server polices(see consent_tracking.md), however the intention is that they may also find a use for features such as "Message of the day".

This is a feature specific to Synapse, but it uses standard Matrix communication mechanisms, so should work with any Matrix client.

User experience

When the user is first sent a server notice, they will get an invitation to a room (typically called 'Server Notices', though this is configurable in homeserver.yaml). They will be unable to reject this invitation - attempts to do so will receive an error.

Once they accept the invitation, they will see the notice message in the room history; it will appear to have come from the 'server notices user' (see below).

The user is prevented from sending any messages in this room by the power levels.

Having joined the room, the user can leave the room if they want. Subsequent server notices will then cause a new room to be created.

Synapse configuration

Server notices come from a specific user id on the server. Server administrators are free to choose the user id - something like server is suggested, meaning the notices will come from @server:<your_server_name>. Once the Server Notices user is configured, that user id becomes a special, privileged user, so administrators should ensure that it is not already allocated.

In order to support server notices, it is necessary to add some configuration to the homeserver.yaml file. In particular, you should add a server_notices section, which should look like this:

server_notices:
   system_mxid_localpart: server
   system_mxid_display_name: "Server Notices"
   system_mxid_avatar_url: "mxc://server.com/oumMVlgDnLYFaPVkExemNVVZ"
   room_name: "Server Notices"

The only compulsory setting is system_mxid_localpart, which defines the user id of the Server Notices user, as above. room_name defines the name of the room which will be created.

system_mxid_display_name and system_mxid_avatar_url can be used to set the displayname and avatar of the Server Notices user.

Sending notices

To send server notices to users you can use the admin_api.