I don't want just anyone to write anything to our relay. But it's easy to fix for relay operators if they do what I was asking about.
I did it for our relay, and also added an improvement to our LNURL server that makes seeing received zaps even more bulletproof, even if other people's relays don't fix it:
The goal of an inbox relay is to allow people to send you events. If you don't allow it, you are not going to get them. Notifications won't show up.
This is why inbox relays are a separate list from Home relays, where you keep your own posts and let everyone download them from.
Be that as it may, it's not necessary to even have a special inbox relay in order to receive zap receipts, and it's obvious from our LNURL server's logs that a lot of people don't request receipts to be published to inbox relays. In fact, it's almost everyone I saw so far.
Also, since inbox relays can easily be spammed or DDoS'ed, I won't set one up until I have proper mitigations for that. Maybe you could point me to learning resources about this?
