29.2 Rule Sets and m4

When building a configuration file using the m4 technique (see Section 19.1, "The m4 Preprocessor" ), sendmail reserves certain rule-set numbers for its own use. Using the m4 technique, you can add rules to those rule sets, but you cannot replace those rule sets with your own. A few m4 keywords are available to make adding rules easier. They affect rule sets 0 through 3 directly and other rule sets indirectly (see Table 19.5 in Section 19.4.3, "Rules and rule sets" ).

The configuration file created with the m4 technique uses quite a few rule sets beyond the base group of 0 through 5. Table 29.1 shows all the rule sets used by the bare bones m4 technique. They are listed numerically, which also just happens to group them by function. The table also includes the name of the file containing the rules for each rule set.

Table 29.1: Rule Sets Used by the m4 Technique

Set	File	Description
S0	m4/proto.m4	Select a delivery agent
S1	m4/cfhead.m4	Process all sender addresses
S2	m4/cfhead.m4	Process all recipient addresses
S3	m4/proto.m4	Preprocess all addresses
S4	m4/proto.m4	Postprocess all addresses
S5	m4/proto.m4	Post alias select a delivery agent
S10	mailer/local.m4	Handle S= for local delivery agent
S11	mailer/smtp.m4	Handle S= for smtp delivery agents
S12	mailer/uucp.m4	Handle S= for uucp delivery agents
S15	mailer/mail11.m4	Handle S= for mail11 delivery agent
S20	mailer/local.m4	Handle envelope R= for local delivery agent
S21	mailer/smtp.m4	Handle envelope R= for smtp delivery agents
S22	mailer/uucp.m4	Handle envelope R= for uucp delivery agents
S25	mailer/mail11.m4	Handle envelope R= for mail11 delivery agent
S30	mailer/local.m4	Handle <@> and masquerading for local delivery agent
S31	mailer/smtp.m4	Handle ALL_MASQUERADE envelope R= for smtp
S40	mailer/local.m4	Handle header R= for local delivery agent
S42	mailer/uucp.m4	Handle header R= for uucp delivery agents
S50	mailer/local.m4	Rules to add local domain (if ALWAYS_ADD_DOMAIN)
S51	mailer/smtp.m4	Convert pseudo-domains to real domains
S52	mailer/uucp.m4	Handle envelope S= for uucp-dom delivery agent
S61	mailer/smtp.m4	Handle ALL_MASQUERADE envelope R= for relay agent
S71	mailer/smtp.m4	Handle envelope header R= for relay agent
S72	mailer/uucp.m4	Handle envelope S= for uucp-uudom delivery agent
S90	m4/proto.m4	Try domain part of mailertable entry
S93	m4/proto.m4	Convert header names to masqueraded form
S94	m4/proto.m4	Convert envelope names to masqueraded form
S95	m4/proto.m4	Canonify mailer:[user@]host syntax to triple
S96	m4/proto.m4	Handle common rule set 3 needs
S98	m4/proto.m4	Handle local part of rule set 0