NAME
    Mail::SpamAssassin::Plugin::Hashcash - perform hashcash verification
    tests

SYNOPSIS
      loadplugin     Mail::SpamAssassin::Plugin::Hashcash

DESCRIPTION
    Hashcash is a payment system for email where CPU cycles used as the
    basis for an e-cash system. This plugin makes it possible to use valid
    hashcash tokens added by mail programs as a bonus for messages.

USER SETTINGS
    use_hashcash { 1 | 0 } (default: 1)
        Whether to use hashcash, if it is available.

    hashcash_accept user@example.com ...
        Used to specify addresses that we accept HashCash tokens for. You
        should set it to match all the addresses that you may receive mail
        at.

        Like whitelist and blacklist entries, the addresses are
        file-glob-style patterns, so "friend@somewhere.com", "*@isp.com", or
        "*.domain.net" will all work. Specifically, "*" and "?" are allowed,
        but all other metacharacters are not. Regular expressions are not
        used for security reasons.

        The sequence %u is replaced with the current user's username, which
        is useful for ISPs or multi-user domains.

        Multiple addresses per line, separated by spaces, is OK. Multiple
        "hashcash_accept" lines is also OK.

    hashcash_doublespend_path /path/to/file (default:
    ~/.spamassassin/hashcash_seen)
        Path for HashCash double-spend database. HashCash tokens are only
        usable once, so their use is tracked in this database to avoid
        providing a loophole.

        By default, each user has their own, in their "~/.spamassassin"
        directory with mode 0700/0600. Note that once a token is 'spent' it
        is written to this file, and double-spending of a hashcash token
        makes it invalid, so this is not suitable for sharing between
        multiple users.

    hashcash_doublespend_file_mode (default: 0700)
        The file mode bits used for the HashCash double-spend database file.

        Make sure you specify this using the 'x' mode bits set, as it may
        also be used to create directories. However, if a file is created,
        the resulting file will not have any execute bits set (the umask is
        set to 111).