Microsoft 365 Notifications to Gmail

[brodgers]

Good afternoon!

Does anyone have their Microsoft 365 configured to send notices, such as file-sharing notices, to an internal user's Gmail mailbox rather than their Exchange mailbox?  In Exchange Admin, I have a connector configured for aspmx.l.google.com and a transport rule to route all messages for our email domain through the connector.

Things are working fine on the Microsoft 365 side.  It is sending notices to Gmail as expected.  My problem is on the Gmail side.  It appears that Gmail is performing SPF checks on the internal M365 servers rather than the SMTP gateway that transfers the message to Gmail.  This is causing the messages to fail SPF and are being sent to spam.

I have include:spf.protection.outlook.com included in our SPF record and have DKIM configured for M365 with the appropriate DNS records.  Why is Gmail testing SPF on internal servers rather than just the SMTP gateway it receives the message from?  Is there any way around this behavior?

Thanks!

Brad

[icrew · Accepted solution]

I don’t have direct knowledge of this specific situation, but perhaps https://support.google.com/a/answer/60730?hl=en has something to do with it?

[brodgers]

@icrew thank you for pointing me in the right direction.  The problem was self-inflicted.  For whatever reason I added the MS365 endpoint IPs as inbound gateways.

[Kim_Nilsson]

Yes, I'm fairly sure that Inbound Gateway should only be used when the MX record points to M365 for the domain address used in Workspace.