HP-UX Mailing Services Administrator's Guide (B2355-91064)

programs to access mail messages as they are being processed, in order to filter meta
information and content. Milter is declared in the configuration file as:
Xname {, field=value}*
Where name is the name of the filter (used internally only) and the field=value pairs
define attributes of the filter.
Enhanced DNS Black Hole List Option
The enhanced DNS Black Hole List (EDNSBL) option is an enhanced version of the
dnsbl feature.
The dnsbl feature rejects mail from hosts in a DNS-based rejection list. The dnsbl
feature is used to enable the blocking of email from open relay sites, dialup sites, or
known spamming sites. This feature is included in the sendmail.cf configuration
file as:
# map for DNS based blacklist lookups
Kdnsbl dns -R A -T<TMP>
The enhanced dnsbl feature is a superset of the dnsbl feature. This feature is
represented in the sendmail.cf file as follows:
# map for enhanced DNS based blacklist lookups
Kenhdnsbl dns -R A -a. -T<TMP> -r5
You must use the /usr/newconfig/etc/mail/cf/cf/gen_cf script to include
the enhdnsbl feature in the sendmail.cf file. You must choose the “5: Enhanced
DNSBL” sub-menu option in the “3: Anti-Spamming Options” main menu option, and
regenerate the sendmail.cf file.
You can use the dns-type database map for the dnsbl and enhdnsbl features.
The enhancement consists of additional arguments, that is, one or more literal addresses
you expect returned when an address is rejected.
Compared to the dnsbl option, you can specify additional arguments (upto 5) to
specify the return values from lookups. Sendmail ignores temporary lookup failures
in the absence of a third argument, which must be either t or a full error message. By
default, any successful lookup generates an error. Otherwise, the result of the lookup
is compared with the supplied arguments, and an error is generated only if a lookup
matches.
Enabling Anti-Spamming Security Features
You must run the gen_cf script to turn on relaying, validating, and checking features.
The access database also allows you to control the message flow. See the section “Using
the Access Database to Allow or Reject Mail Messages” (page 84) for more information.
Configuring Sendmail to Reject Unsolicited Mail 83