I read an article in the Wall Street journal that was a summary of the latest Demo conference. A service called SenderBase was introduced there. This service keeps a public database email volume for various IPs and their domains. Admins could use this to set up their white/gray/black lists. I see this is a viable option to allow allow ISP's to avoid filtering mail after they have received it. Related to this service is Bonded Sender, which is similar to another post's suggestion--registered MTA's. It requires email senders to post a bond thhat they are not sending post. Senders with a bond posted could be considered safe to put on your whitelist. These types of shared databases could possibly help ISP's and system admins at least to stop some spammers from taking up bandwidth by refusing connections from them.
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I read an article in the Wall Street journal that was a summary of the latest Demo conference. A service called SenderBase was introduced there. This service keeps a public database email volume for various IPs and their domains. Admins could use this to set up their white/gray/black lists. I see this is a viable option to allow allow ISP's to avoid filtering mail after they have received it. Related to this service is Bonded Sender, which is similar to another post's suggestion--registered MTA's. It requires email senders to post a bond thhat they are not sending post. Senders with a bond posted could be considered safe to put on your whitelist. These types of shared databases could possibly help ISP's and system admins at least to stop some spammers from taking up bandwidth by refusing connections from them.