Why do so few mail providers support Port 587?

Fri Feb 25 17:03:14 UTC 2005

On 2/25/2005 10:51 AM, Nils Ketelsen wrote:

> On Thu, Feb 24, 2005 at 11:36:40PM -0500, Valdis.Kletnieks at vt.edu wrote:
> I force anyone, who wants to relay to use SMTP-AUTH on port 25. Only mails
> for local delivery are accepted without AUTH. Whats point
> in opening another port? 

There are lots of secondary benefits. One of my favorites is that I can
reject mail session on port 25 from hosts that claim to be in my domain
(all such mail is authenticated on port 587 or is coming from a
pre-configured list of servers that already hit an exception, so any other
connections on port 25 that HELO as ehsco.com are lying). There are lots
of these kinds of non-trivial benefits.

-- 
Eric A. Hall                                        http://www.ehsco.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/