Microsoft Delays Retirement of Basic Authentication for SMTP AUTH
Microsoft has delayed the retirement of basic authentication for the SMTP AUTH client submissions protocol to 2027 or beyond. New tenants will be the first to be blocked and Microsoft will disable basic authentication for SMTP AUTH in a way that existing tenants can reenable the protocol. Eventually, we’ll get a date for final retirement sometime in 2027. These things take time! https://office365itpros.com/2026/01/29/smtp-auth-basic-retirement/
M365 tenant emails marked as spam (SCL:5, CAT:PHISH) despite perfect authentication
Hello, Our business emails from our M365 tenant are consistently marked as spam when sent to other M365 tenants, despite perfect email authentication. Technical status: - SPF: Pass ✓ - DKIM: Pass ✓ (recently enabled) - DMARC: Pass ✓ (recently enabled) - Composite Authentication: Pass (reason=100) ✓ But messages are still marked as: - X-MS-Exchange-Organization-SCL: 5 - X-Forefront-Antispam-Report: CAT:PHISH;SFV:SPM We suspect a tenant reputation issue, possibly because the tenant ran for months without DKIM enabled. Now that all authentication is correct, how can we request a reputation review? Thank you!
