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Re: Making users to use port 587 for submission emails

On Sat, 10 Sep 2005, Sasa Stupar wrote:

--On 10. september 2005 11:02 +0100 Paul Howarth <paul city-fan org> wrote:

On Sat, 2005-09-10 at 11:48 +0200, Sasa Stupar wrote:

I am running Sendmail 8.13.4 on FC4 with cyrus2. I have configured
sendmail  to listen on ports 25 and 587. Since all of the client mail
software use  port 25 by default instead of 587, how do I make users to
use 587 and deny  access to 25? Something like: when they try to connect
to port 25, they get  back error - you are not a server so you must use
port 587.

Where are these users located?

You can turn off relaying for everywhere except localhost, which will
give any non-local clients a "relaying denied" error; using port 587
they will need to authenticate and that will override the relay check.

You can't easily tell the different between an MUA and an MTA connecting
to your port 25 - they are both acting as SMTP clients. This is why port
25 blocking became necessary in the first place.

Paul Howarth <paul city-fan org>

Maybe this should be the next step in evolution of the mail servers - to recognize MUA and MTA correctly. This is only my thinking.

SMTP could use a lot of redesign, I guess they never knew back then what they do now in terms of problems with spam, encryption, authentication, etc. I'm suprised something hasn't been created to intend as a replacement, like ipv6 is to ipv4.

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