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 ...

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