I think per post.

I’m working on the UX designs in Figma for this at the moment.

Some relays would be free (but in my opinion end up getting spammed) but other relays require micro-payments to post. Still cheap for users, but makes it too expensive to run large spam farms. This would then incentivise relay runners.

It’s interesting to note that when digital cash was first being discussed, it was with an idea to stop email spam as one use case to make it too expensive to send millions of spam e-mails.

You could also replace “likes” with “tips” which again is a way to send sats to that user and tally the count of Sats. This incentivises the users (they can earn Sats for posts others find funny / useful).

Could consider financial penalty for bad-actors. Those that post “bad content” are downvoted with potential financial penalty. Again, incentivising good behaviour. This one is more tricky and would require further consideration.