[Suicide Junkie]

FTL isn't really a part of the SE4 universe. Consider that all contact is lost once the Last warppoint connecting two civs is closed.

Relay sats would be nice. I would imagine that it would be very interesting (though a humans-only game) if you required at least one sat, ship or base with a special comm component in each starsystem through which you wanted to send Messages.

In order to deal with a race on the other side of the galaxy, you would have to have either a very long string of sats, or go through a few middlemen races (who get to see your message), or possibly have a colony (embassy) set up inside their territory.
To avoid the cheap way out of gifting embassy moons to other players, the palace ability could be implemented. Allow only one facility (or cloaked ship/base for paranoid races) with that ability at any one time, and comms would be measured from that point.
Losing your palace (anarchy!) means you cannot communicate with other races until a new one is built.