[78027] in North American Network Operators' Group
Re: Why do so few mail providers support Port 587?
daemon@ATHENA.MIT.EDU (Daniel Senie)
Wed Feb 16 09:21:39 2005
Date: Wed, 16 Feb 2005 09:20:44 -0500
To: nanog@merit.edu
From: Daniel Senie <dts@senie.com>
In-Reply-To: <2147483647.1108518124@[172.17.1.152]>
Errors-To: owner-nanog-outgoing@merit.edu
At 04:42 AM 2/16/2005, Owen DeLong <owen@delong.com> 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.
