Tool is only accessible with the container's network, to avoid potential spam/DOS.
Indeed, one could just call the container's public URL with a forged request to redirect POST requests to an arbitrary server.
With this modification, one could still use Filter Hook with an arbitrary URL, but the call should come from Wekan (i.e. mass move/create cards), which is not worth it.

With STARTTLS and all configuration possible (and followed https://github.com/wekan/wekan/wiki/Troubleshooting-Mail and other issues), we just get ERRORS like 'not logged in' or 'unable to verify the first certificate'.

Still doesn't work with traefik