The $t macro contains
the current date and time represented as an integer. The value of
$t is set in two places:
When sendmail first begins to run, it presets
several date-oriented macros internally to the date and time it was
run. Among those are the $a,
$d, $b, and
$t macros. This initialization is done after the
configuration file is read.
Each time a new envelope is created, the $d,
$b, and $t macros are given a
default that is the current time.
$t is intended for use in configuration-file
header definitions. $t is transient. If it is
defined in the configuration file or in the command line, that
definition can be ignored by sendmail. Note that
a $& prefix is necessary when you reference
this macro in rules (that is, use $&t, not
$t).
