@mayday @moffintosh That's how fediblock works. Underlying protocol doesn't matter much.

The idea of fediblock is to share blocklists and apply them collectively. Some extend it further to blocking by association (block not just violators but also their main connections) and blocking by non-compliance (block those who refuse to follow your blocking policy).

This indeed results in breaking the network into constellations unreachable from each other. In open decentralized system like email users expect to have connectivity with the absolute majority of the network. It stops being the case.

Imagine having an email account which blocks traffic with half of most popular mail providers.