How to setup Multiple Domains with one External IP?

Question asked by Archie Quintana - 8/25/2017 at 9:28 AM

Answered

Hi,

I would like to know how to setup SmarterMail to host multiple domains with just one external static IP. This is what I have so far:

-   I have configured the server where SmarterMail is installed with a static private IP 192.168.10.6
-   I have configured 192.168.10.7 and 192.168.10.8 as secondary private IPs for server where SmarterMail is installed on.
-   I configured in SmarterMail domain mail.domain1.com which is binded to IP 192.168.10.7
-   I configured in SmarterMail domain mail.domain2.com which is binded to IP 192.168.10.8
-   When I telnet internally to IP 192.168.10.6 on port 25, I get “220 Email-Server" which means good.
-   When I telnet internally to IP 192.168.10.7 on port 25, I get “220 mail.domain1.com" which means good.
-   When I telnet internally to IP 192.168.10.8 on port 25, I get “220 mail.domain2.com" which means good.
-   I opened port 25 on my firewall so that traffic on port 25 is routed from the external IP to internal IP 192.168.10.6 (the server where SmarterMail is installed on)
-   When I telnet externally to mail.domain1.com on port 25, I get “220 Email-Server Service Ready” instead of “mail.domain1.com Service Ready” which means no good.
-   When I telnet externally to mail.domain2.com on port 25, I get “220 Email-Server Service Ready” instead of “mail.domain2.com Service Ready” which means no good.

These results tell me that the servers are running and ready and that the routing policy for port 25 is working fine as it is routing to the right IP specified in the policy.

The goal: I should be able to telnet each of these domains and have it connect to the right server. Can someone help?

Thanks,

Archie.

P.S. Please note that I can only route traffic on port 25 from the external IP to one internal IP.

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Employee Replied

8/29/2017 at 1:26 PM

Employee Post Marked As Answer

Archie,

I wanted to post in here since you also opened a ticket with us to assist with this issue. I wanted to get the information out on the community in case someone else wants to setup this scenario.

In order for each domain to have it's own banner response for example '220 mail.domain1.com' you would need a public IP for each separate banner response due to how the hostnames are mapped within SmarterMail and bound to each IP address.

Since you're behind a NAT, you would need multiple WAN IP's to perform a 1:1 mapping for the IP hostnames.

Regardless of banner response, your users across your multiple domains can authenticate to any IP you have listening. So users from domain1.com, domain2.com, domain3.com could all authenticate when connecting to either internal IP address configured within SmarterMail.

I hope this helps !

Paul Blank Replied

8/27/2018 at 6:37 AM

But it appears that SM will only SEND email from the email server's primary IP address. Is this correct?

echoDreamz Replied

8/27/2018 at 7:17 AM

I'd sell my soul for SM to have proper IP rotation built into it... Just sayin'.

Paul Blank Replied

8/27/2018 at 8:05 AM

(Actually meant this response to go with another thread, but I'm leaving it here as well as it might be relevant...)

OK so this is the setting (in v15)...

Domain (globe icon) / [click on domain] / Edit / Technical / Outbound IPv4 (dropdown)

The question is: does this setting work as it should? ... I will be testing this shortly.

And if it does work, how can you assign a cert. (for outbound TLS) to that domain by its IP address?

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