Mailing List Message #106563
From: Tom Rymes <>
Subject: Re: How to require authentication for SMTP
Date: Mon, 11 Sep 2017 08:21:44 -0400
To: CommuniGate Pro Discussions <>
I would go with Nicolas' suggestion to forward another port to 587 on the CGP box, but I am also wondering how much of an issue it is if the port does not require authentication. So long as you are not an open relay, any device connecting to that port could only submit mail destined for your users, or have I overlooked something?


On 09/07/2017 8:05 PM, Nicolas Hatier wrote:

Another way would be to open another port on your firewall, but redirect to CGP's 587.

*Nicolas Hatier, ing.* < <>>
Niversoft idées logicielles -

On 2017-09-06 10:59, Mark J Strawcutter wrote:
For those instances where 587 is blocked, can you provide them with a VPN service so they can open 587 thru that?


On 9/6/2017 3:39 AM, Fred.Zwarts wrote:
WE have set up a system with two SMTP ports. One is port 25, used for receiving mails sent to our users. The other one is port 587, the submission port, which is used by our users to send mail elsewhere. Port 587 requires authentication, which makes sure that only valid users send mail elsewhere. This port 587 is also used by our users when the are traveling, and when they are on networks of other providers.
Now it turns out that some providers block port 587. I don't understan why, but that does not matter, it is a fact and we cannot change it.
So, I want to offer my users another port, with the same properties as port 587. However, I cannot find a way to require authentication. It seems that port 587 is configured automagically to require authentication.
Does someone know how this can be accomplished? If not, is it a good idea for a new feature.

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