I have found that greylisting based on the Spamhaus sbl-xbl list massively reduces spam. Setting that up on my backup MX
resulted in
all traffic through it stopping when my primary MX is up.
James,
Are you using greylisting or blacklisting with Spamhaus? My understanding of blacklisting is that blacklisting uses a DNS blacklist, such as Spamhaus. My understanding of greylisting is when your MTA sends back a temporary failure the first time in X number of days where it sees a new sender/receiver/mail server IP address triplicate. Please clarify.
Thanks, Barry
I believe he means that he is only greylisting incoming email when the server is listed in spamhaus. All other mail comes through without being greylisted (resulting in normal delivery times)
--Bill