NAME¶

Mail::Milter::Module::MailDomainDNSBL - milter to accept/reject mail whose sender domain matches a DNSBL

SYNOPSIS¶

    use Mail::Milter::Module::MailDomainDNSBL;

    my $milter = new Mail::Milter::Module::MailDomainDNSBL('foo.spamlist.dom');

    my $milter2 = &MailDomainDNSBL('foo.spamlist.dom'); # convenience

    $milter2->set_message('Mail from %M disallowed');

DESCRIPTION¶

This milter module rejects any mail from a sender's domain (in the MAIL FROM part of the SMTP transaction, not in the From: header) matching a given DNS Blocking List (DNSBL). It can also function as a whitelisting Chain element; see "accept_match()". The check used by this module is a simple "A" record lookup, via the standard "gethostbyname" lookup mechanism. This method does not require the use of Net::DNS and is thus typically very fast.

METHODS¶

new(DNSBL)

new(DNSBL, MATCHRECORD[, ...])

new(DNSBL, SUBREF)

Creates a MailDomainDNSBL object. DNSBL is the root host hierarchy to use for lookups. Three methods of matching can be used:

 

If no additional arguments are provided, the match succeeds if there is any address entry present for the DNSBL lookup; the values are not examined.

 

If one or more MATCHRECORD 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 DNSBL lookup, the match succeeds.

 

If a SUBREF (reference to a subroutine; may be an anonymous inline "sub{}") is supplied, it is called for each of the address records returned by the DNSBL 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 "inet_ntoa()" or "unpack", and the domain name being checked by the DNSBL.

accept_match(FLAG)

If FLAG is 0 (the default), a matching DNSBL will cause the mail to be rejected.

 

If FLAG is 1, a matching DNSBL will cause this module to return SMFIS_ACCEPT instead. This allows a "MailDomainDNSBL" to be used inside a "Mail::Milter::Chain" container (in accept_break(1) mode), to function as a whitelist rather than a blacklist.

 

This method returns a reference to the object itself, allowing this method call to be chained.

ignore_tempfail(FLAG)

If FLAG is 0 (the default), a DNSBL lookup which fails the underlying DNS query will cause the milter to return a temporary failure result (SMFIS_TEMPFAIL).

 

If FLAG is 1, a temporary DNS failure will be treated as if the lookup resulted in an empty record set (SMFIS_CONTINUE).

 

This method returns a reference to the object itself, allowing this method call to be chained.

set_message(MESSAGE)

Sets the message used when rejecting messages. This string may contain the substring %M, which will be replaced by the matching e-mail address, or %L, which will be replaced by the name of the matching DNSBL.

 

This method returns a reference to the object itself, allowing this method call to be chained.

AUTHOR¶

Todd Vierling, <tv@duh.org> <tv@pobox.com>

SEE ALSO¶

Mail::Milter::Object