We can see it ourselves. We use rabbitmq for incoming (and maybe outgoing, it’s been a while since I looked at how it is) federation. So, you can see the queues there. For incoming (from rabbitmq) and outgoing there are also queues (symfony messenger) and these handle failures and can be configured and can be queried.

After the upgrade I just took the default configuration again (because it seems queue names changed). But I used to have various rules setup in rabbitmq for retries and it took a fair few tries before the messages ended up in the proper “failed” queue (which needs manual action to retry). Some items you eventually need to clear (instances that just shutdown, or instances that lost their domain for example). They will never complete.

But it’s not exposed in any way to my knowledge. Well unless people have their rabbitmq web interface open and without login of course.