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A comment on Ask HN: cheap ways to host your own email server?. Parent comment

Re:Ask HN: cheap ways to host your own email server? by mindslight on Friday January 24, 2014 @03:22PM (#7117694)
Most ISPs block outbound tcp port 25, which is why you'll likely need to setup your ISP's smtp server as a smarthost for a consumer connection.

FWIW running a personal mail server on Linode for 8 years, I've never had a remote mail server refuse acceptance due to my IP address not being on some protocartel whitelist.

I have had a few annoying false positives from Mailavenger, but clearly that's not my config that's broken :>

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Re:Ask HN: cheap ways to host your own email server? by josho on Friday January 24, 2014 @05:04PM (#7118434)
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.

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Re:Ask HN: cheap ways to host your own email server? by mindslight on Friday January 24, 2014 @05:48PM (#7118731)
Well 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.
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