Clients don’t have the ability to receive notes from relays which they are not connected to. The intersection of relays used by both users (if they want to communicate or see each other) must not be an empty set :)

Some see this as an issue, but I assure you it is not. It’s the only way a decentralized open free network like Nostr can scale.

However, I am mirroring some n-to-n relays (and anyone can mirror, really) to help bootstrap the network.

In the near future, Nostream will be able to seed (and perhaps remain connected) from other relays.

Let me know if that answers your questions.