Feature: keep notifying on unknown devices or auto delete unknown devices

[sbe-arg]

I would love the idea of keep receiving notifications when unknown devices are found every X scans or X hours.

Or a feature to auto delete unknown devices after 12h or 24h something like that.

[HoreaM]

I think that's a really good idea, would be really interested in getting notifications every time an unknown device switches status from offline to online.