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Use SM Free as an Open Relay to route mail to Outbound Gateway
Question asked by TJ - 10/6/2021 at 11:49 AM
Unanswered
Hi all, I have a SmarterMail 7929 server hosted out in the cloud that functions as my primary server. I have a bunch of automation that happens in my office from various systems that generates and sends email to an old, internal SM 13.6 instance that was setup as an Outbound Gateway to forward email to my public server (the internal subnet was whitelisted and the SM 13.6 server was effectively an open relay for my internal systems to use).

I upgraded my old internal SM to 7929 Free Edition and now it seems the internal system does not operate like and open relay, it only accepts and forwards email to the primary SM server if the sending email address matches the single domain I configured on the internal server.

I configured the internal SM server with whitelisted IP's for my internal network, configured the outbound gateway and set the single domain to use the outbound gateway I defined and I set the inbound message delivery to external - use host address.

What I want is for any system in my whitelist to send email via the internal SM server and have all email routed to the outbound gateway for actual sending to the destination, but it seems I can't do that. It only works that way if the sending address domain is the same as the single domain setup in the internal SM Free instance.

Is there anyway of setting up the internal SM server to forward all email (sent to and from any email) to be routed via the outbound gateway?

Thanks, TJ

4 Replies

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Patrick Mattson Replied
Not sure if this helpful, but I was trying to set up a couple backup servers. On the Inbound gateway for each of my backup servers I had down the CIDR address. Kyle discovered, not sure if he is still researching, but I had only put a single IP.

Example: I had 10.10.10.0/24, but had to be specific and use 10.10.10.20

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Zach Sylvester Replied
Employee Post
Hello TJ, 

Thanks for posting on the community. Having an open relay server is never a good idea. Instead setting up an outbound gateway would be best. You can read more about how to setup an outbound gateway here. Then on your mailserver you can configure it to use this gateway. Make sure to configure authentication as having an open relay server will get you on some blacklists. 

Please let me know if this helps.

Best Regards, 
Zach Sylvester System/Network Administrator SmarterTools Inc. (877) 357-6278 www.smartertools.com
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TJ Replied
Hi Zach, that's exactly what I did, I setup an outbound gateway on my internal SM server that should forward all email to my main SM server that should then deliver email to the world. The internal server is only accessible by my internal systems, and although technically I attempted to set it up the internal as an open relay by whitelisting the internal subnet, it is not publicly accessible at all.

The issue is I'm trying to sending an email using an email address that doesn't exist on the internal server (not the sender email address or the recipient email address) and I would expect that the email should be routed to my public SM server via the outbound gateway for delivery. The email is accepted by the internal SM server with the outbound gateway, but it does not hand off the email via the gateway...

TJ

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Zach Sylvester Replied
Employee Post
Hey TJ, 

It looks like you have maintenance and support. I'm going to open a ticket for you so we can look more into this. 

Best Regards, 
Zach Sylvester System/Network Administrator SmarterTools Inc. (877) 357-6278 www.smartertools.com

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