[115403] in North American Network Operators' Group
Re: Is your ISP blocking outgoing port 25?
daemon@ATHENA.MIT.EDU (J.D. Falk)
Thu Jun 18 16:37:31 2009
Date: Thu, 18 Jun 2009 14:36:58 -0600
From: "J.D. Falk" <jdfalk-lists@cybernothing.org>
To: nanog@nanog.org
In-Reply-To: <20090618201445.GA38466@gweep.net>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Joe Provo wrote:
> On Thu, Jun 18, 2009 at 03:36:44PM -0400, Zhiyun Qian wrote:
>> It has been long heard that many ISPs block outgoing port 25 for the purpose
>> of reducing spam originated from their network.
>
> Yes, it is standard practice for non-server accounts and most dynamic-only
> accounts; only allow unauthenticated smtp traffic to your own smtp servers.
> If you are not running server-to-server traffic at the end of that broadband
> pipe, then you should be shifting your userbase to authenticated on the SUBMIT
> port [587] anyway...
The Messaging Anti-Abuse Working Group (MAAWG) published recommendations for
managing port 25 traffic a few years ago, and even then it had already been
a widely-accepted best practice for nearly a decade.
http://www.maawg.org/port25
--
J.D. Falk
Return Path Inc
http://www.returnpath.net/
