I am currently evaluating both OpenProject 14.4.2 and the Plane 0.22.0 project management platforms. I am self-hosting these projects in docker inside an Ubuntu 24.04 vm, on different ports attached to a static IP, running on ProxMox. Attempting to set up and test the email functionality, in OpenProject I receive this error
An error occurred while sending mail (Connection refused - connect(2) for "localhost" port 25)
and from within Plane I receive this error
Network connection error. Please check your internet connection.
Since everything else seems to work, these errors suggest to me that this might be a docker/ProxMox network issue, but I don't have a clue exactly where to look. Looking for guidance, thanks.