Dear Marketers,
We want to bring your attention to an important upcoming change announced by Microsoft (Outlook) that will impact users sending bulk emails to Outlook.com, Hotmail.com, and other Microsoft-hosted inboxes. This update focuses on strengthening email authentication to improve inbox security and reduce spam. These measures will help reduce spoofing, phishing, and spam activity, empowering legitimate senders with stronger brand protection and better deliverability.
Microsoft's New Requirements for Bulk Senders:
Microsoft is introducing new requirements for domains sending more than 5,000 emails per day. Starting May 5th, 2025, Outlook will begin enforcing stricter email authentication standards.
Key Changes to Be Aware Of:
Mandatory SPF (Sender Policy Framework): Your sending domain must pass SPF authentication. Ensure your domain's DNS record accurately lists all authorized IP addresses and hosts that send emails on your behalf.
Mandatory DKIM (DomainKeys Identified Mail): Your emails must pass DKIM authentication. This validates the integrity and authenticity of your emails.
Mandatory DMARC (Domain-based Message Authentication, Reporting, and Conformance): Your domain must have a DMARC record in place, and alignment with either SPF or DKIM (preferably both for optimal deliverability).
Impact on Non-Compliant Senders:
Initial Routing to Junk: After May 5th, 2025, emails from high-volume senders that do not comply with these authentication requirements will initially be routed to the Junk folder.
Future Rejection: Microsoft has stated that in the future, non-compliant emails will be rejected entirely to further protect their users.
Recommendations for Zoho Marketing Automation Users:
As users of Zoho Marketing Automation, especially if you send bulk email campaigns that might exceed 5,000 emails per day to Microsoft-hosted inboxes, it's crucial to take the following steps now to ensure your email deliverability is not affected:
Review Your DNS Records: Audit your SPF, DKIM, and DMARC records for the domains you use to send emails through Zoho Marketing Automation. Verify that they are correctly configured and accurately reflect your sending infrastructure.
Ensure SPF Passes: Confirm that your SPF record includes all necessary sending sources for Zoho Marketing Automation.
Ensure DKIM is Implemented: Verify that DKIM signing is properly set up for your sending domains within Zoho Marketing Automation.
Implement DMARC: If you haven't already, implement a DMARC record in your DNS. Starting with p=none allows you to monitor your email authentication results before moving to stricter policies.
Configure Custom Return Path: This dedicated custom return-path address allows you to receive detailed notifications about email bounces, enabling you to analyze delivery issues and proactively manage your email lists.
Follow Email Hygiene Best Practices: While not strictly mandatory yet, adopting the following practices will further enhance your deliverability and sender reputation:
Use compliant and valid "From" and "Reply-To" addresses.
Include functional and easily accessible unsubscribe links.
Maintain clean email lists and manage bounces effectively.
Practice transparent mailing practices with clear subject lines and proper consent.
Next Steps for You:
Prepare Now: Review and update your SPF, DKIM, and DMARC records immediately.
Help Resources: If you need assistance with setting up SPF, DKIM, or DMARC, refer to Zoho Marketing Automation's help documentation.
This update from Microsoft underscores the increasing importance of proper email authentication for ensuring reliable email delivery. By taking proactive steps now, you can safeguard your email campaigns and maintain strong deliverability to Outlook inboxes.
We will continue to monitor this situation and provide any further updates or guidance relevant to using Zoho Marketing Automation. Keep an eye on our community forums and announcements.

If you have any questions or concerns regarding this, please don't hesitate to reach out to our support@zohomarketingautomation.com or engage in the community forums.
Happy Marketing!
The Zoho Marketing Automation Team