/usr/share/sendmail/cf/hack/spamtrap.m4 is in sendmail-cf 8.15.2-8.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 | divert(-1)dnl
#-----------------------------------------------------------------------------
# $Sendmail: ./spamtrap.m4,v 8.12.0 2001/09/24 12:00:00 cowboy Exp $
#
# hack(spamtrap) config file for building Sendmail
#
# Courtesy of jeff@sdsc.edu (Jeff Makey)
# via c.m.s posting Sat, 8 Sep 2001 07:44:26 +0000 (UTC)
#
# Spamtrap addresses go into the access file like this:
#
# To:spamtrap@pandora.orbl.org POISON
# To:Friend@public.com POISON
#
#-----------------------------------------------------------------------------
#
divert(0)dnl
LOCAL_CONFIG
# provide access to macros as a map
Kmacro macro
LOCAL_RULESETS
######################################################################
### spamtrap: handle spamtrap(POISON) users
###
######################################################################
#
# This is not only redundant, but fails with feature(`delay_checks')
#
#SLocal_check_mail
# Clear the "poison recipient" indicator macro for this message.
#R$* $: $(macro {PoisonRecipient} $) $1
SLocal_check_rcpt
#
# Spamtrap addresses go into the access file like this:
# To:spamtrap@pandora.orbl.org POISON
#
# Certain recipients are "poison" and cause the
# message to be rejected for all recipients.
R$* $: $1 $| $1 create workspace to right of $|
R$* $| $* <$+> $* $1 $| $3 focus on part in angle brackets
R$* $| $+ $: $1 $| $>SearchList <!To> $| <E:$2> <>
R$* $| <POISON> $: $1 $| $(macro {PoisonRecipient} $@ POISON $)
R$* $| $* $: $1 delete workspace
Scheck_eoh
R$* $: $&{PoisonRecipient}
RPOISON $#error $@ 5.7.1 $: 550 Mail sent to spam lists is not accepted here
#
# With a "To:Friend@public.com POISON" entry in the access file the
# following ruleset will block certain types of spam too:
#
# Certain To headers are sure-fire spam signatures.
HTo: $>CheckTo
SCheckTo
R$+ , $+ $@ $1 , $2 do not try to verify complex addresses
R$* $: $1 $| $>SearchList <!To> $| <E:$1> <>
R$* $| <POISON> $#error $@ 5.7.1 $: 550 Mail sent by spamware is not accepted here
R$* $| $* $: $1 delete lookup result
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