Outlook/Hotmail Email Delivery Requirements Update

Incident Report for Crucial Hosting

Update

We are continuing to work on a fix for this issue.

Posted Nov 09, 2026 - 19:02 AEDT

Identified

Microsoft has recently strengthened email authentication requirements for messages sent to Outlook.com, Hotmail.com, Live.com, and other Microsoft-hosted email services.

As a result, domains that do not have properly configured email authentication records may experience email delivery issues, including message rejection, filtering, or delivery delays.

Customers should ensure the following DNS records are configured and valid for all mail-sending domains:

SPF (Sender Policy Framework)
DKIM (DomainKeys Identified Mail)
DMARC (Domain-based Message Authentication, Reporting and Conformance)
A commonly observed rejection error is:

"Message rejected: Message lacks SPF/DKIM/DMARC authentication records."

This particularly affects customers using externally hosted DNS (Remote DNS/External Nameservers), as these records must be added and maintained with their DNS provider.

Customers are encouraged to verify that all required authentication records are present and fully propagated to avoid email delivery issues when sending to Outlook, Hotmail, or Live recipients.

Reference: https://techcommunity.microsoft.com/blog/microsoftdefenderforoffice365blog/strengthening-email-ecosystem-outlook%E2%80%99s-new-requirements-for-high%E2%80%90volume-senders/4399730

Customers who are using our shared NS have been fixed already.

Posted Nov 09, 2026 - 11:58 AEDT

This incident affects: Web Hosting Services and Reseller Hosting Services.