Outbound mail gateway
If you have the legacy free edition of Google Apps, upgrade to G Suite to get this feature.
An outbound mail gateway is a server through which all mail sent from your domain passes. The gateway typically processes the mail in some way — such as archiving it or filtering out spam — before delivering the mail.
When you use an outbound mail gateway, the G Suite mail servers pass all outgoing mail from your domain to the gateway server. You configure the gateway server to accept a stream of mail from the G Suite mail servers. You may also need to update your DKIM configuration or the Sender Policy Framework (SPF) record for your domain.
By default, when messages are routed to your outbound gateway server, G Suite Gmail checks to see if secure transport (TLS) is supported by your outbound gateway server. If so, G Suite Gmail delivers the message using secure transport. To enforce that messages are routed to your outbound gateway server only using secure transport, you can consider setting up your outbound gateway and make sure that the Require TLS delivery option is checked.
After you configure an advanced Gmail setting, it may take up to one hour for that configuration to propagate to individual user accounts. You can track prior changes under Admin console audit logTo configure an outbound mail gateway
- Sign in to the Google Admin console.
- From the dashboard, go to Apps > G Suite > Gmail > Advanced settings.
- In the Organizations section, highlight the top-level org.
- Scroll down to the Outbound gateway section.
- In the Outbound gateway text box, enter the IP address of the outbound mail gateway server.
- Save your changes.
- We recommend that you configure your outbound server to accept and forward email only from the G Suite mail servers in order to prevent your outbound server to be used as an open mail relay.
The configuration steps differ depending on the gateway server. For information about the IP addresses of the G Suite mail servers, see Google IP address ranges.