diff --git a/matrix/synapse/README.md b/matrix/synapse/README.md
index f7cfddf..90062a9 100644
--- a/matrix/synapse/README.md
+++ b/matrix/synapse/README.md
@@ -408,7 +408,10 @@ See for more options [Synapse's documentation](https://element-hq.github.io/syna
 # TURN
 
 Check for more information about [how to configure the TURN
-server](../coturn). Once you've set up your TURN server, configure it in
+server](../coturn) or [LiveKit](../element-call#livekit). You probably want
+LiveKit, but read on if you choose coturn.
+
+Once you've set up your TURN server, configure it in
 Synapse, in `conf.d/turn.yaml`:
 
 ```
@@ -430,3 +433,59 @@ the [Synapse documentation](https://element-hq.github.io/synapse/latest/server_n
 to see how to configure that.
 
 It's also necessary for moderation ([see Draupnir](../draupnir)).
+
+
+## Server Notices
+
+Server notices allow administrators to send messages to users, much like the
+`wall` functionality in UNIX/Linux.
+
+Add this bit of info to `conf.d/server_notices.yaml`:
+
+```
+server_notices:
+  system_mxid_localpart: server
+  system_mxid_display_name: "Server Notices"
+# system_mxid_avatar_url: "mxc://matrixdev.example.com/QBBZcaxfrrpvreGeNhqRaCjG"
+  room_name: "Server Notices"
+# room_avatar_url: "mxc://matrixdev.example.com/QBBZcaxfrrpvreGeNhqRaCjG"
+  room_topic: "Room used by your server admin to notice you of important
+information"
+  auto_join: true
+```
+
+This means that the user sending the messages (who isn't really a user anyway)
+is `server@example.com`, with the display name `Server Notices`. The room that users receive
+these messages in is called the same. The room will be created if it doesn't
+yet exist, every user that receives a server message will be put in a room
+with that name.
+
+Every user gets his own room, so if you send a server notice to 100 users,
+there will be (at least) 100 rooms by that name, all containing 1 user.
+
+The option `auto_join` means that users will automatically join the room as
+soon as it's created. They can leave afterwards, but they'll put into it again
+as soon as they receive another server message.
+
+The two commented out options are the avatars for user and room. This is a bit
+tricky. You'll need to upload an image to a room first, so that it's present
+in the media store. Then you can refer to it by the ID it gets, in the way
+shown above. These avatars will only be set or changed when you send a server
+notice.
+
+Important bit: you must upload these pictures to an unencrypted room. Pictures
+in an encrypted room are... well... encrypted, and that causes a problem for
+the thumbnailer. Pictures in encrypted rooms are stored as MIME type
+`application/octet-stream`, you want one of the formats you configured under
+[Homeserver Blocking](#blocking). Or, if you haven't defined a whitelist, at
+least an image mimetype...
+
+You can find the ID of the picture in the database (table `local_media_repository`)
+or, more conveniently, in [Synapse-Admin](../synapse-admin), which is also
+where you'll want to go if you want to send a server notice.
+
+In Synapse-Admin, open the User tab, select the user(s) you want to send a
+notice to, and click "Send Server Notices".
+
+If the result is that you're returned to the login screen of Synapse-Admin,
+there was an error sending the notice. Check the Synapse logs.