Active Incident

Updated a few seconds ago

[HSE20260122-01-I] Incident: Partial service disruption: Inbound/Outbound email workflowPartial Service Disruption

Incident Status

Partial Service Disruption

Components

Email Inbound, Email Outbound

Locations

USA


January 22, 2026 22:08 CET
January 22, 2026 21:08 UTC
IDENTIFIED

We have confirmed that the issue is external and related to Microsoft 365. The errors "531 \<domain\> cannot be resolved" and "451 4.3.2 Temporary server error. Please try later ATTR2" occur because the M365 MX records (e.g., .*.mail.protection.outlook.com) are currently not resolving due to DNS problems on Microsoft's side. As a result, we cannot retrieve the IP addresses needed to deliver emails to Microsoft tenants. To avoid message loss during this incident, we are temporarily converting 531 rejects into deferrals, so affected emails will be queued instead of bounced. This may increase the size of the mail queue, but ensures that no messages are rejected while Microsoft resolves their DNS issues. Customers using the Continuity Service can continue sending and receiving emails while the issue on Microsoft's side is being resolved.

January 22, 2026 21:38 CET
January 22, 2026 20:38 UTC
INVESTIGATING

We are currently investigating reports of emails being rejected with a "531 cannot be resolved" error. The root cause is under analysis. Other services are not affected. In addition, there is an ongoing incident on Microsoft's side. Email traffic, both outgoing and incoming, addressed to Microsoft tenants is being deferred with a "451 4.3.2 temporary server issue" error. https://admin.cloud.microsoft/#/servicehealth/:/alerts/MO1221364

AI Recipient Validation




Operational


365 Permission Manager




Operational


365 Total Backup




Operational


365 Total Protection




Operational


365 Multi-Tenant Manager




Operational


Advanced Threat Protection




Operational


API




Operational


Control Panel - General




Operational


Control Panel - Config / Deployment




Operational


Control Panel - Email Live Tracking




Operational


Control Panel - Backup & Compliance Services




Operational


Email Signature and Disclaimer




Operational


Email Inbound




Partial Service Disruption


Email Outbound




Partial Service Disruption


Email Continuity




Operational


Email Archiving




Operational


Email encryption: Websafe




Operational


Email encryption: S/MIME




Operational


Hornet.email




Operational


IMAP/POP3 Services




Operational


Mailbox Migration Tool




Operational


Security Awareness Service




Operational


Ticketsystem




Operational


Web Filter




Operational


Website




Operational


External Services

Zendesk

Locations