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.IX Title "Mail::Milter::Module::MailDomainDNSBL 3pm"
.TH Mail::Milter::Module::MailDomainDNSBL 3pm "2023-01-22" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
Mail::Milter::Module::MailDomainDNSBL \- milter to accept/reject mail whose sender domain matches a DNSBL
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&    use Mail::Milter::Module::MailDomainDNSBL;
\&
\&    my $milter = new Mail::Milter::Module::MailDomainDNSBL(\*(Aqfoo.spamlist.dom\*(Aq);
\&
\&    my $milter2 = &MailDomainDNSBL(\*(Aqfoo.spamlist.dom\*(Aq); # convenience
\&
\&    $milter2\->set_message(\*(AqMail from %M disallowed\*(Aq);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This milter module rejects any mail from a sender's domain (in the \s-1MAIL
FROM\s0 part of the \s-1SMTP\s0 transaction, not in the From: header) matching a
given \s-1DNS\s0 Blocking List (\s-1DNSBL\s0).  It can also function as a whitelisting
Chain element; see \f(CW\*(C`accept_match()\*(C'\fR.  (This is known as a \*(L"\s-1RHSBL\*(R"\s0 check
in some anti-spam lingo.)
.PP
The check used by this module is a simple \*(L"A\*(R" record lookup, via the
standard \*(L"gethostbyname\*(R" lookup mechanism.  This method does not require
the use of Net::DNS and is thus typically very fast.
.SH "METHODS"
.IX Header "METHODS"
.RS 4
new(\s-1DNSBL\s0)
.Sp
new(\s-1DNSBL,\s0 MATCHRECORD[, ...])
.Sp
new(\s-1DNSBL, SUBREF\s0)
.Sp
Creates a MailDomainDNSBL object.  \s-1DNSBL\s0 is the root host hierarchy to use
for lookups.  Three methods of matching can be used:
.Sp
If no additional arguments are provided, the match succeeds if there is
any address entry present for the \s-1DNSBL\s0 lookup; the values are not
examined.
.Sp
If one or more \s-1MATCHRECORD\s0 values are supplied, they are string
representations of IPv4 addresses.  If any of these match record values is
the same as any address record returned by the \s-1DNSBL\s0 lookup, the match
succeeds.
.Sp
If a \s-1SUBREF\s0 (reference to a subroutine; may be an anonymous inline
\&\f(CW\*(C`sub{}\*(C'\fR) is supplied, it is called for each of the address records
returned by the \s-1DNSBL\s0 lookup.  The subroutine should return 0 or undef to
indicate a failed match, and nonzero to indicate a successful match.  The
subroutine receives two arguments: a binary-encoded four byte scalar that
should be transformed as needed with \f(CW\*(C`inet_ntoa()\*(C'\fR or \f(CW\*(C`unpack\*(C'\fR, and the
domain name being checked by the \s-1DNSBL.\s0
.Sp
accept_match(\s-1FLAG\s0)
.Sp
If \s-1FLAG\s0 is 0 (the default), a matching \s-1DNSBL\s0 will cause the mail to be
rejected.
.Sp
If \s-1FLAG\s0 is 1, a matching \s-1DNSBL\s0 will cause this module to return
\&\s-1SMFIS_ACCEPT\s0 instead.  This allows a \f(CW\*(C`MailDomainDNSBL\*(C'\fR to be used inside
a \f(CW\*(C`Mail::Milter::Chain\*(C'\fR container (in \f(CWaccept_break(1)\fR mode), to
function as a whitelist rather than a blacklist.
.Sp
This method returns a reference to the object itself, allowing this method
call to be chained.
.Sp
ignore_tempfail(\s-1FLAG\s0)
.Sp
If \s-1FLAG\s0 is 0 (the default), a \s-1DNSBL\s0 lookup which fails the underlying \s-1DNS\s0
query will cause the milter to return a temporary failure result
(\s-1SMFIS_TEMPFAIL\s0).
.Sp
If \s-1FLAG\s0 is 1, a temporary \s-1DNS\s0 failure will be treated as if the lookup
resulted in an empty record set (\s-1SMFIS_CONTINUE\s0).
.Sp
This method returns a reference to the object itself, allowing this method
call to be chained.
.Sp
check_superdomains(\s-1NUM\s0)
.Sp
If no match is returned by checking the domain name verbatim, recurse
one level upward at a time and attempt the check again.  If \s-1NUM\s0 is
positive, the recursion will stop after \s-1NUM\s0 recursions; if negative,
the recursion will stop when abs(\s-1NUM\s0) domain levels have been reached.
The default is 0, meaning that no recursion will be done.
.Sp
For example, when checking the domain name \s-1FOO.BAR.BAZ.COM,\s0 NUM=1 will
also check \s-1BAR.BAZ.COM\s0; NUM=\-1 will check \s-1BAR.BAZ.COM, BAZ.COM,\s0 and \s-1COM.\s0
.Sp
This method returns a reference to the object itself, allowing this method
call to be chained.
.Sp
set_message(\s-1MESSAGE\s0)
.Sp
Sets the message used when rejecting messages.  This string may contain
the substring \f(CW%M\fR, which will be replaced by the matching e\-mail
address, or \f(CW%L\fR, which will be replaced by the name of the matching
\&\s-1DNSBL.\s0
.Sp
This method returns a reference to the object itself, allowing this method
call to be chained.
.RE
.SH "AUTHOR"
.IX Header "AUTHOR"
Todd Vierling, <tv@duh.org> <tv@pobox.com>
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Mail::Milter::Object
.SH "POD ERRORS"
.IX Header "POD ERRORS"
Hey! \fBThe above document had some coding errors, which are explained below:\fR
.IP "Around line 78:" 4
.IX Item "Around line 78:"
You can't have =items (as at line 90) unless the first thing after the =over is an =item