I'm exploring filtering on the relay so I have to be somewhat less strict than what individuals might want to filter. Ultimately, if the Pessimism spam bot wants me to relay their spam, I want to offer that service, too, for a price. I don't see relays as providing access to subscribers. Clients should still filter as needed but until I figured out how to price repetitive messages every minute, I'd rather block them.
Discussion
What about charging by kB or megabyte sent to your server? Like a prepaid plan.
You can set the price by seeing how much the server costs you monthly and how much MB was processed by you, divide it and put your profit on top
I want to run the relay with this and much more. Currently, relays have a extremely primitive price structure. All paid relays charge a flat rate for getting white-listed to send events to that relay. Anybody can download these events a million times for free.
I'm working on a relay that keeps track of all resource usage attributed to pubkeys.