Why no-one has mentioned Delta Chat yet? https://runtimeterror.dev/self-hosted-chatmail-relay-for-delta-chat/

Just to be sure: this is a script, right? Sitting somewhere? Not just a command put directly in the config?

I think you might have to ask in https://github.com/lutris/lutris/issues I’m out of ideas

Do you have space in the path of your script?

Is it executable?