sendmail 8.13 Companion

A Useful Table

The sendmail program reserves all lowercase letters, punctuation characters, and digits for its own use. For multi-character names, it reserves all those that begin with an underscore or a lowercase letter. Table 21-1 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.^[29]

Table 21-1. Reserved macros

Macro	sendmail text reference	Description
$_	21.9.1[3ed]	RFC1413-validation and IP source route
$a	21.9.2[3ed]	The origin date in RFC822 format
${addr_type}	21.9.3[3ed]	Is address recipient/sender or header/envelope?
${alg_bits}	21.9.4[3ed]	The number of bits in the TLS cipher
${auth_authen}	21.9.5[3ed]	RFC2554 SASL AUTH credentials
${auth_author}	21.9.6[3ed]	RFC2554 SASL AUTH= parameter
${auth_ssf}	21.9.7[3ed]	SASL AUTH encryption key length
${auth_type}	21.9.8[3ed]	SASL Authentication mechanism used
$b	21.9.9[3ed]	The current date in RFC2822 format
${bodytype}	21.9.10[3ed]	The ESMTP (Extended SMTP) BODY parameter
$B	21.9.11[3ed]	The BITNET relay (mc configuration, deprecated)
$c	21.9.12[3ed]	The hop count
${cert_issuer}	21.9.13[3ed]	Distinguished name of certificate signer
${cert_md5}	21.9.14[3ed]	MD5 of cert certificate
${cert_subject}	21.9.15[3ed]	The cert subject
${cipher}	21.9.16[3ed]	Cipher suite used for connection
${cipher_bits}	21.9.17[3ed]	TLS encryption ...