Comment by Aachen

Or a deposit system: pay 2€ for a human to read this message, you'll get it back if it's not spam

What if the human marks it as spam but you're actually legit? Deposit another 2€ to have the platform (like Hackerone or whichever you're reporting via) give a second opinion, you'll get the 4€ back if you weren't spamming. What to do with the proceeds from spammers? The first X euros of spam reports go to upkeep of the platform, the rest to a good cause defined by the projects to whom the reports were submitted because they were the ones who had to deal with reading the slop so they get at least this much out of it

Raise deposit cost so long as slop volume remains unmanageable

This doesn't discriminate against people who aren't already established, but it may be a problem if you live in a low-income country and can't easily afford 20€ (assuming it ever gets to that deposit level). Perhaps it wouldn't work, but it can first be trialed at a normal cost level. Another concern is anonymity and payment. We hackers are often a paranoid lot. One can always support cash in the mail though, the sender can choose whether their privacy is worth a postage stamp