diff --git a/container_to_container/README.md b/container_to_container/README.md
index 328336c..5398371 100644
--- a/container_to_container/README.md
+++ b/container_to_container/README.md
@@ -1,2 +1,31 @@
+# A different approach
+
+This approach uses container to container communication. This requires that the bug in /overleaf/services/web/app/src/Features/User/UserRegistrationHandler.js is fixed. see https://github.com/overleaf/overleaf/issues/1206
+
+EmailHandler.promises.sendEmail('registered', { 
+
+is missing a await. 
+
+await EmailHandler.promises.sendEmail('registered', { 
+
+I fixed the file out side an mount it in the overleaf compose.yaml via
+    volumes:
+      - /root/overleafserver/UserRegistrationHandler.js:/overleaf/services/web/app/src/Features/User/UserRegistrationHandler.js
+
+# More restrictive
+
+We can block users via the tools/blocked_users.json. And we allow domains for tools/allowed_domains.json for which creation of account is allowed. e.g. uni-bremen.de allows @*.uni-bremen.de and @uni-bremen.de. Furthmore, invited people can also create accounts. 
+
+# No google
+
+I replaced the google captcha because of data privacy reasons... Just, kidding I wasn't able to make it run. Thus I replaced by a python solution. 
+
+# How to use this version
+
 Set a secret key in tools/secret_key.json. Then build the docker image with make_image.sh.
 
+Set tools/allowed_domains.json
+
+
+
+A full working setup can be found here https://github.com/davrot/overleaf