(Received):. (66.55.160\.|66.55.161\.)

FAQ Email Antispam Techniques and Email Filtering
1

Can you suggest a way of rewriting rule below that would ensure that the class C "66.55.160" is blocked but "166.55.160.*" would
pass?

:0
* ^(Received):.*(66.55.160\.|66.55.161\.|66.55.162\.|66.55.163\.|66.55.164\.|66.55.165\.|66.55.166\.|66.55.167\
.)
{
  LOG="(ISKIMARO vendare 1)  "
  :0
  /dev/null
}

[begs the obvious]
At least until I can verify no false SPAM positives, I need more
logging than /etc/mail/access

66.55.160 DISCARD

When the filter does get rotated into /etc/mail/access, I prefer not to use a REJECT, because I don't want to give any feedback to SPAMMERS which would tend to alert them to mail me from one of their other servers.