[lug] Idea for ISPs to limit spam/zombies

[D. Stimits]

I was thinking about how many domains I can no longer email, due to 
black hole lists marking my comcast servers as spam. It gets really 
irritating to suffer because of someone else's zombie machine. An ISP 
could block port 25 to anyone other than their own servers, but this is 
the lobotomize approach, it isn't a real solution. So here's an idea I'm 
wondering what people think of, especially anyone who does any kind of 
email service...

In their configuration, such as web login pages to the ISP where the 
non-commercial user can set email preferences, you have an item called 
"unblock port 25/SMTP". If they check this, they are allowed to send to 
any port 25 destination...if not then they can send only to the ISP's 
SMTP port. In order to check this though, they *must* set a CC email 
address at their ISP, and all outgoing mail to port 25 of any server 
other than their own ISP's results in a copy of the email to this email 
box. The named email box would have some limit on it like 10 MB, and if 
it fills up, the port 25 block automatically re-activates. The user 
would have to empty that email box before they could send again to 
outside SMTP. As an option, perhaps they would also have to call the ISP 
on the phone each time to get port 25 re-activated. Perhaps it would be 
useful for the CC email account to also be reachable ONLY via web 
interface, and it would present an image with a second password...it 
would require a human to read the image in order to get into the account 
and to delete emails, no automated deletion would work.

Should someone be infected by a virus or be an open relay, their email 
account would fill up, and they would get a copy of everything they've 
sent. The brakes would be applied when the account fills, and I'm 
assuming a fill of around 10 MB. Non-commercial users could still send 
anywhere, but they would be forced to watch how much traffic they are 
sending out.

D. Stimits, stimits AT comcast DOT net