Microsoft is implementing some new safety measurements to strengthen the email authentication for domains sending more than 5,000 emails per day. Please keep in mind, that these changes have nothing to do with our filtering but only with the filtering of Outlook itself.
What's Changing?
For domains sending over 5,000 emails per day, Outlook will soon require compliance with SPF, DKIM, DMARC. Non‐compliant messages will first be routed to Junk. If issues remain unresolved, they may eventually be rejected. Senders will soon start requiring compliance with the following requirements:
- SPF (Sender Policy Framework)
- Must Pass for the sending domain
- Your domain's DNS record should accurately list authorized IP addresses/hosts
- DKIM (DomainKeys Identified Mail)
- Must Pass to validate email integrity and authenticity
- DMARC (Domain-based Message Authentication, Reporting, and Conformance)
- At least p=none and align with either SPF or DKIM (preferably both)
To make sure, that you are not affected by the rejection and that you can monitor your SPF/DKIM/DMARC compliance, we recommend using our DMARC Manager: https://www.hornetsecurity.com/en/services/dmarc-manager/. DMARC Manager simplifies email authentication management, enhancing security and brand trust by protecting against fraud, impersonation and phishing attacks.
Google and Yahoo already made some steps for stricter requirements. For reference, see the following links:
Google: https://support.google.com/a/answer/81126?hl=en#zippy=%2Crequirements-for-all-senders
Yahoo: https://senders.yahooinc.com/best-practices/
For more information about the Microsoft changes, see the following link: https://techcommunity.microsoft.com/blog/microsoftdefenderforoffice365blog/strengthening-email-ecosystem-outlook%E2%80%99s-new-requirements-for-high%E2%80%90volume-senders/4399730