Julian Kippels writes:

I would like to configure Postorious in a way to disable the functionality to delete a list. Is there a way to do this?

You would have to patch the code. There are four levels to this:

1. You can hide the delete button on the list owner's view of the list page. (Someone who knows the URL can still invoke the callback.)
2. You can remove the delete callback from the list view code. (Someone with access to the REST API can still use that.)
3. You can remove the delete callback from the REST API. (This probably is enough, although it's possible that the 'mailman' command line utility could still do it -- I haven't checked.)
4. You can remove the delete function entirely. Depending on why you want to do this, 1 might be sufficient.

I think it is unlikely that we would implement a configuration option for this. It's generally our philosophy that if you don't trust someone not to do such things, you shouldn't make them a list owner. If an owner wants to disable their list, there are several ways to do it (spam controls, emergency moderation, mass unsubscribe). But you could ask.