It’s a well known fact that quite a bit of spam comes from the Comcast network. Now that Comcast has blocked TCP port 25 (the port used for e-mail sending), spam from their network has dropped 35%. Now if we could just convince other gigantic ISPs to do the same, life would be good. I know that geeks sometimes run SMTP servers on their home servers, but if they’re smart, they’ll just change the port used and they won’t have any trouble. I know Bend Cable (oh, sorry, Bend Broadband) blocks at least ports 21 (FTP) and 80 (HTTP) so the server I have at home that I backup files from work to runs on different ports so I can still access it. Geeks are smart — common users that have their computers zombied for spam are not.
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Er, I think they mean they block outbound traffic destined for port 25 on any remote host.. save their own smtp servers. You can’t change ports to get around that, since the service on the remote machine would have to provide itself on a different port.
D’oh. You’re right, that would make more sense, and that’s what they did (it wouldn’t work for me because I routinely use an outside SMTP server on my laptop so I don’t have to change settings all the time). They should still block it on the outside, just the same.
They only block people that appear to be spammers, I assume by volume of mail going out. Regular users will not be blocked.