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.IX Title "Mail::SpamAssassin::Plugin::Hashcash 3pm"
.TH Mail::SpamAssassin::Plugin::Hashcash 3pm "2021-03-26" "perl v5.28.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
Mail::SpamAssassin::Plugin::Hashcash \- perform hashcash verification tests
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  loadplugin     Mail::SpamAssassin::Plugin::Hashcash
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Hashcash is a payment system for email where \s-1CPU\s0 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.
.SH "USER SETTINGS"
.IX Header "USER SETTINGS"
.IP "use_hashcash { 1 | 0 }   (default: 1)" 4
.IX Item "use_hashcash { 1 | 0 } (default: 1)"
Whether to use hashcash, if it is available.
.IP "hashcash_accept user@example.com ..." 4
.IX Item "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.
.Sp
Like whitelist and blacklist entries, the addresses are file-glob-style
patterns, so \f(CW\*(C`friend@somewhere.com\*(C'\fR, \f(CW\*(C`*@isp.com\*(C'\fR, or \f(CW\*(C`*.domain.net\*(C'\fR will all
work.  Specifically, \f(CW\*(C`*\*(C'\fR and \f(CW\*(C`?\*(C'\fR are allowed, but all other metacharacters
are not.  Regular expressions are not used for security reasons.
.Sp
The sequence \f(CW%u\fR is replaced with the current user's username, which
is useful for ISPs or multi-user domains.
.Sp
Multiple addresses per line, separated by spaces, is \s-1OK.\s0  Multiple
\&\f(CW\*(C`hashcash_accept\*(C'\fR lines is also \s-1OK.\s0
.IP "hashcash_doublespend_path /path/to/file   (default: ~/.spamassassin/hashcash_seen)" 4
.IX Item "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.
.Sp
By default, each user has their own, in their \f(CW\*(C`~/.spamassassin\*(C'\fR 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.
.IP "hashcash_doublespend_file_mode            (default: 0700)" 4
.IX Item "hashcash_doublespend_file_mode (default: 0700)"
The file mode bits used for the HashCash double-spend database file.
.Sp
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).