Use Proxmox gateway as a Mail Relay

[Laurie]

Hi

I was wondering if it is possible to configure the gateway product as a mail relay.

That is, no exchange server just internet mail received from the external firewall, checked and cleaned by Proxmox gateway and then feed back to the external firewall.

I have read the doco and I don't see how this could be done, but I would like to check in case I've misunderstood the purpose of the product.

Thanks

 

[Stoiko Ivanov]

You need to have a destination for that e-mail - what exactly is your plan and what are you trying to set up?
(you want the MX record of the domains you want to handle to point to the external IP where your PMG is reachable - then the question remains where PMG should send the mail further (it cannot rely on the public MX record, as that points to itself...)

 

[Laurie]

Hi

We have Microsoft Business Central (BC)running in 0365.

To send emails from BC via SMTP requires an SMTP server address to be configured in the email setup wizard. You might enter the Twilio SendGrid here if that was your Mail Relay service.

We would like similar functionality as SendGrid but instead use an onprem Mail Relay server.

I was hoping that Proxmox gateway could be used in the same way as Twilio’s sendGrid

You say “you want the MX record of the domains you want to handle to point to external IP..”

This is the bit I am confused about. Are the domains you are referring to the email addresses domains that BC will be sending emails to? i.e the customers emails that will be receiving emails from us.

If so, we don’t know ahead of time what these domains will be.

Or are you referring to the domain of the MX record that assigned to the PMG server.


The second question about where PMG will send the emails further will be a smart host server and it will send them to the Internet in the same way as mail from our onprem exchange server

Thanks

 

[Stoiko Ivanov]

I have not experience with Microsoft Business Central - probably best to ask Microsoft support how to configure mail-relaying with one of their products. (Maybe someone from the community has experience with this and chimes in)

In general you should be able to configure PMG as outbound relaying server by simply:
* point your SMTP server (microsoft BC's email setup wizard) to send to PMG's internal port (defaults to 26)
* add the IP of your server to the trusted Networks
as I'm not sure if your Microsoft BC runs with one dedicated IP, or is hosted by Microsoft in their cloud - keep in mind that it's not a good idea to allow all their Cloud-IPs as trusted networks - because else everybody else using BC will be able to send through your PMG..

This is the bit I am confused about. Are the domains you are referring to the email addresses domains that BC will be sending emails to? i.e the customers emails that will be receiving emails from us.

I was explaining how inbound relaying works (MX record for _your_ domain points to PMG, which sends the mails forward to your Mailserver)
for outbound relaying PMG will simply send the mails to the internet ...

I hope this explains it!