The End-To-End Internet (was Re: Blocking MX query)

Sean Harlow sean at
Wed Sep 5 15:51:54 UTC 2012

On Sep 5, 2012, at 11:46, Greg Ihnen wrote:

> But as someone pointed out further back on this thread people who want to
> have their mail servers available to people who are on the other side of
> port 25 filtering just use the alternate ports. So then what does filtering
> port 25 accomplish?

The alternate port 587 is for users of that mail server to send mail through it, presumably authenticated, not for receipt of random mail from the internet.  This allows those users to relay email through their server unaffected while behind a port 25 block.  Configuring it to accept all messages on that port would defeat the purpose.
Sean Harlow
sean at

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