diff --git a/20.1--Installation-using-egroupware-docker-RPM-DEB-package.md b/20.1--Installation-using-egroupware-docker-RPM-DEB-package.md
index a0e6861..c43a331 100644
--- a/20.1--Installation-using-egroupware-docker-RPM-DEB-package.md
+++ b/20.1--Installation-using-egroupware-docker-RPM-DEB-package.md
@@ -8,6 +8,7 @@
 * modifications to docker-compose file are now kept in a separate docker-compose.override.yml to ease updates
 * Rocket.Chat is no longer automatic installed, as you should install your https certificate before!
 * EGroupware now uses TypeScript instead of plain JavaScript to ease client-side development
+* mail servers can be [configured to notify EGroupware about new mails](https://github.com/EGroupware/egroupware/wiki/IMAP-Push-Notifications)
 
 ### 20.1 packages are currently available only in a special repository
 The following example is for Ubuntu 20.04 (replace ```20.04``` with ```18.04``` or ```16.04```, or ```xUbuntu_20.04``` with ```Debian_10```):