diff --git a/POSTINSTALL.md b/POSTINSTALL.md
index c807a72..4cd5b78 100644
--- a/POSTINSTALL.md
+++ b/POSTINSTALL.md
@@ -1,8 +1,8 @@
-<sso>
-This app integrates with the Cloudron User Management. Cloudron users can register
-themselves using any client and use Matrix Synapse.
-</sso>
+Account ids are created with the username and the second level domain under which the
+app is installed e.g. `@username@domain.com`.
 
-**IMPORTANT: See the [docs](https://cloudron.io/documentation/apps/synapse/) on
-how to complete setup and start using this app.**
+For federation to work, the second level domain has to be configured to serve up the
+`.well-known/domain.com/matrix` URI. See the 
+[federation docs](https://cloudron.io/documentation/apps/synapse/) on
+how to do this.