security/hashcash 1.22 NetBSD

Hashcash is a denial-of-service counter measure tool. It's main current use is to help hashcash users avoid losing email due to content based and blacklist based anti-spam systems.

The hashcash tool allows you to create hashcash tokens to attach to
emails you send, and to verify hashcash tokens attached to emails you
receive. Email senders attach hashcash tokens with the X-Hashcash:
header. Vendors and authors of anti-spam tools are encouraged to exempt
mail sent with hashcash from their blacklists and content based
filtering rules.