Nine times out of ten: unfinished SPF, DKIM and DMARC DNS records. Google does not enable DKIM automatically, and that step gets skipped. Check that all three show PASS under the message’s “Show original” view.
How to fix it: SPF, DKIM and DMARC in order.
A deliverability check is part of our free Workspace audit, and DNS authentication is included in every setup project.
