It seems to me if the speed of light were infinitely fast, then chain letters need not be illegal. My reasoning: the chain-letter pyramid scheme needs an exponentially increasing number of participants sending money to the top of the list. Soon the needed number outstrips the world's population, the pyramid collapses and most participants are defrauded.
Now, the observable universe is every potential source of light so near the Doppler shift from spacetime's expansion can't reduce a signal's frequency to zero before we get it. The shift size depends on the speed of light.
Were light infinitely fast, the observable universe would be infinitely large. By the Law of Large Numbers, the Conservation of Energy would be exact despite quantum mechanics. Thus by the ergodic principle, everything would repeat in time and space infinitely often. As one populated Earth exists, then so would infinitely many populated Earths. Therefore, just as one can match one-to-one the integers and the even numbers, every person -- including all the participants -- can get all the participants they need. As the scheme honestly works it could be legal.
Trivia: Singapore saw an aurora on 25 September 1909. Source: 1982 Guinness Book of World Records, Norris McWirther.
Currently Reading: 2150 A.D., Thea Alexander. The first 108 pages are mostly lectures on how way more evolved the future is, with everyone tall and buff and handsome and sexually unrepressed and un-jealous and un-competitive and bowing to their mental superiors (Thea doesn't say that explicitly). Plus they have telepathy and psychokinesis and astral projection and stuff. So far the likeable character is the only woman who chose to appear middle-aged (she likes the variety; I like anyone who, given the choice of Standard Perfection, does something different). She says, ``Whenever you really ask for help, and not just pity, you will always receive it,'' which I keep telling my friends ... Still, Future Earth looks a lot like Hippie Twink Muck.