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sendmail 8.13 Companion
book

sendmail 8.13 Companion

by Bryan Costales, George Jansen, Claus Assmann, Gregory Neil Shapiro
September 2004
Intermediate to advanced content levelIntermediate to advanced
192 pages
10h 12m
English
O'Reilly Media, Inc.
Content preview from sendmail 8.13 Companion

Chapter 9. DNS and sendmail

DNS stands for Domain Name System. A domain is any logical or physical collection of related hosts or sites, such as example.gov or www.example.gov.

What’s New with V8.13

  • The dnsbl feature (7.2.1[3ed]) no longer uses the host database-map type to look up addresses. Instead, it uses the dns database-map type (Section 9.1.1 [V8.13]).

  • The DNSBL_MAP_OPT mc macro (Section 9.1.1 [V8.13]) has been added so that you may tune the database-map flags used with the dnsbl feature.

  • The check_relay rule set (7.1.1[3ed]) is now called with the value of ${client_name} macro (21.9.20[3ed]), allowing it to deal with bogus DNS entries (Section 9.1.2 [V8.13]).

Feature dnsbl Uses dns Database-Map

The dnsbl feature (7.2.1[3ed]) is used to enable the blocking of email from open relay sites, dial-up sites, or known spamming sites. It does so by invoking the RBL technique, which is discussed in 7.2[3ed].

Prior to V8.13, the dnsbl feature employed the host database-map type (23.7.9[3ed]) to look up addresses. Beginning with V8.13, this feature now uses the dns database-map type (23.7.6[3ed]).

The default declaration for the dns database-map for this feature looks like this:

Kdnsbl dns -R A -T<TMP>

If you wish to change the type of the lookup, you may redefine the dns -R A part of the expression:

define(`DNSBL_MAP´, `dns -R TXT´)
FEATURE(dnsbl, ...)

Here, the DNSBL_MAP redefines the lookup so that it performs TXT record lookups instead of A record lookups. Note that DNSBL_MAP must be defined ...

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Publisher Resources

ISBN: 0596008457Catalog PageErrata