This is 2m now. 1 month expiry. 

Another 2m if you make shareable mute lists into a NIP. First come first serve. Other devs must agree that it’s a sensible way of doing it and might be willing to implement. nostr:note1kdmw8jdwt2uvzg6rrezzytyjk458w8ajgqw0ew875acaklq4rs5qedd8gx