Update i_u_m_install.md

docs/i_u_m_install.md

@@ -80,6 +80,9 @@ Done!
 
 You can now access **https://${MAILCOW_HOSTNAME}** with the default credentials `admin` + password `moohoo`.
 
+   !!! info
+   If you are not using mailcow behind a reverse proxy, you should [redirect all HTTP requests to HTTPS](https://mailcow.github.io/mailcow-dockerized-docs/u_e-80_to_443/).
+
 The database will be initialized right after a connection to MySQL can be established.
 
 Your data will persist in multiple Docker volumes, that are not deleted when you recreate or delete containers. Run `docker volume ls` to see a list of all volumes. You can safely run `docker-compose down` without removing persistent data.