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s/most/some/ If an ISP blocks port 25 then it means they'll have a bunch of support calls from people who's email client doesn't send email because SMTP is blo
by josho 13y ago
s/most/some/
If an ISP blocks port 25 then it means they'll have a bunch of support calls from people who's email client doesn't send email because SMTP is blocked. So, in my experience not many ISPs do that anymore. Besides it isn't actually an effective way to stop spam.
- mindslight 13y agoWell I currently see both Sonic.net and Verizon blocking outbound tcp/25, which is the extent of my limited sample. According to RFC4409, mail submission is supposed to be done on tcp/587 these days. And no matter how effective at actually stopping spam in general, I suspect tcp/25 is blocked out of a desire to not end up on IP blacklists due to botnetted customers.