North American Network Operators Group

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Re: Why do so few mail providers support Port 587?

  • From: Daniel Senie
  • Date: Wed Feb 16 09:22:23 2005

At 04:42 AM 2/16/2005, Owen DeLong <[email protected]> wrote:
If you accept unauthenticated mail on port 587, the problem isn't the
spam you will receive, it is the spam you will forward.
ONLY if that unauthenticated sender is also permitted to RELAY.

That is not a given. The decision to relay or not is separate from whether the user is authenticated with SMTP AUTH or some other method (IP address range, smtp-after-pop), just as it is on port 25.

I'm not arguing for leaving port 587 wide open, but there are uses to allowing potr 587 and 25 to have the same rules, and not permit relay on either. This is necessary where SMTP-after-POP is still in use, for example, but does NOT imply open relay. Yes, authorized users (authorized by AUTH, smtp-after-pop, or IP address ranges) can still send mail (including spam, subject to enforcement) but that does NOT constitute open relay.