Microsoft warns Gmail blocks some Outlook email as spam, shares fix

Microsoft confirmed that some Outlook.com users with country-specific domains are having messages to Gmail blocked as spam, with Gmail citing low sending-domain reputation; as a temporary workaround, Microsoft advises sending via an Outlook.com alias. Google references its new bulk sender guidelines—requiring proper authentication and stricter spam thresholds—with gradual rejection of non-compliant traffic starting April 2024 and broader enforcement in June, urging senders to adjust to improve deliverability.