That sounds good, I've learned how to do SPF for outgoing mail but not yet DKIM - one day! I saw a talk a few years ago on aggregating DNS lookups for insight

That sounds good, I've learned how to do SPF for outgoing mail but not yet DKIM - one day! I saw a talk a few years ago on aggregating DNS lookups for insight into many things, spam included. The presenter said he had great results from simply blocking mail from domains that were less than 24hrs old.