Sendmail, 3rd Edition

Alphabetized sendmail Macros

The sendmail program reserves all lowercase letters, punctuation characters, and digits for its own use. For multicharacter names, it reserves all those that begin with an underscore or a lowercase letter. Table 21-7 lists all the macro names that have special internal meaning to sendmail. Included in this list are macros that are used by the mc configuration technique.^[12]

Table 21-7. Reserved macros

Macro	§	Description
$_	$_	RFC1413-validation & IP source route
$a	$a	The origin date in RFC822 format
${addr_type}	${addr_type}	Is address recipient/sender header/envelope
${alg_bits}	${alg_bits}	The number of bits in the TLS cipher
${auth_authen}	${auth_authen}	RFC2554 AUTH credentials
${auth_author}	${auth_author}	RFC2554 AUTH= parameter
${auth_ssf}	${auth_ssf}	AUTH encryption keylength
${auth_type}	${auth_type}	Authentication mechanism used
$b	$b	The current date in RFC2822 format
${bodytype}	${bodytype}	The ESMTP (Extended SMTP) BODY parameter
$B	$B	The BITNET relay (mc configuration, deprecated)
$c	$c	The hop count
${cert_issuer}	${cert_issuer}	Distinguished name of certificate signer
${cert_md5}	${cert_md5}	MD5 of cert certificate
${cert_subject}	${cert_subject}	The cert subject
${cipher}	${cipher}	Cipher suite used for connection
${cipher_bits}	${cipher_bits}	TLS encryption key length
${client_addr}	${client_addr}	The connecting host’s IP address
${client_flags}	${client_flags}	The nature ...