I have read op.me carefully and spent a lot of time on
comp.mail.sendmail seeking the confirmation of imposibility of using
mailer local or esmtp in rulesets other than 0 (and subroutine of 0)
and 5 (only local?), id est in the check_(relay|mail|
rcpt),Check(Subject|Received|MessageID|etc). But I found out only the
following in the op.me
"The $# syntax should only be used in ruleset zero, a subroutine of
ruleset zero,
or rulesets that return decisions (e.g., check_rcpt).",
"Rule set 0 is one of the few rule sets that may use $# ...Rule set 5
can also return a $#" (Sendmail book)
and recomendation to use procmail or milter to redirect mail based on
Subject content (comp.mail.sendmail).
But "rulesets that return decision" may use only error or discard
mailers, doesn't they?