My apologies to the list for sending HTML email.
A plain text version:
As a point of discussion regarding port 25 filtering. Let's look at two possible future models:
For both these models, today's weak-security SMTP is still used for email. The ISP having the sender of email is called "SendISP". The ISP with the recipient mailserver is called "RecvISP".
MODEL A: ISPs filter at the source; spam is reduced
ISP's filter outgoing port 25 traffic from networks; allowing exceptions.
SendISP limits outgoing mail. RecvISP has less incentive to block incoming.
If a customer of SendISP want's to run a mail server, SendISP has motivation to
make an exception.
Customer's wanting exceptions tend to be rare.
MODEL B: ISPs filter incoming mail traffic; spam is reduced.
ISP's increase the effectiveness of blacklists and locating dynamic IPs; allowing exceptions as requested by the mail server admins/users. (Filtering may occur at network level or in mail servers.)
SendISP does not limit outgoing mail. RecvISP has strong incentives to block.
If a customer of SendISP want's to run a mail server, RecvISP has almost no motivation to make a blacklist exception. RecvISP is more concerned about _their_ customers/users.
Which model really provides us with the best of both worlds: less spam yet more freedom to innovate? I would say model A does.
However, I am not convinced of this. Please pick apart my models..
(As if I have to ask...)
John
