I m not deep in technical but this is Satoshi talking about spam in the #Bitcoin network I don't know how can be implemented in #nostr
"Interestingly, one of the e-gold systems already has a form of
spam called "dusting". Spammers send a tiny amount of gold dust
in order to put a spam message in the transaction's comment field.
If the system let users configure the minimum payment they're
willing to receive, or at least the minimum that can have a
message with it, users could set how much they're willing to get
paid to receive spam"