[Mimedefang] Spammers - was Re: md_check_against_smtp_server and md_graphdefang_log

[kd6lvw at yahoo.com]

--- On Tue, 3/26/13, Les Mikesell <lesmikesell at gmail.com> wrote:
> Besides which, real spammers are much more likely to take the trouble
> to set up SPF properly than an ordinary person who just wants to send
> you a message that you'd want to see.

1)  When a spammer uses SPF, recipients KNOW the spammer domains and servers and automatically block them.  Such is most effective with a shared reporting namespace of spammers (like spamhaus or spamcop).  Unless they're registering domains with stolen credit cards, burning alot of domains like that is going to get expensive, even with the cheapest registration services.

2)  Spammers seem to be avoiding spoofing domains that have proper SPF records set up, while not embracing SPF for their own domains.  (cf. http://spf-all.com/  - where only 0.6% of domains having SPF records used "+all" -- 139,000 of 88 million.)