Why are Hotmail emails being rejected after setting up DMARC?
Michael Ko
Co-founder & CEO, Suped
Published 15 Apr 2025
Updated 17 Aug 2025
5 min read
Discovering that your Hotmail (Outlook.com) emails are being rejected after diligently setting up DMARC can be incredibly frustrating. You’ve taken a significant step toward email security and brand protection, only to find your legitimate messages aren't reaching their intended recipients.
This usually indicates an underlying authentication issue that DMARC, especially with a p=reject policy, is now actively enforcing. Understanding why these rejections occur and how to properly align your email authentication is key to restoring your email deliverability.
Microsoft, which includes Hotmail, Outlook.com, and Live.com, has significantly tightened its email authentication requirements. They are leading the charge in enforcing DMARC policies, meaning that if your emails fail their DMARC checks, they are likely to be rejected outright when your policy is set to p=reject.
A typical rejection message might look like Access denied, sending domain [yourdomain.com] does not pass DMARC verification and has a DMARC policy of reject. This specific error indicates that while you have a DMARC record, the email failed either SPF or DKIM authentication, and because your DMARC policy is set to reject, the recipient server is blocking the message.
It is crucial to understand that simply having a DMARC record isn't enough; the underlying SPF and DKIM authentication must pass and align with your DMARC policy. If either of these fails, and your DMARC policy is set to p=reject, Hotmail will reject the email.
Common causes of DMARC failure
The most common reasons for DMARC failures and subsequent rejections by Hotmail stem from issues with SPF and DKIM authentication. DMARC relies on the successful validation of either SPF or DKIM, and crucially, their alignment with the From: header domain.
SPF alignment failures
Domain Mismatch: SPF alignment requires that the domain in the Return-Path header (or MailFrom) matches or is a subdomain of the domain in the visible From: header. Often, third-party senders use their own domains in the Return-Path field, leading to SPF alignment failure.
Incorrect SPF Record: Your SPF record might be missing legitimate sending IPs or contain syntax errors, causing valid emails to fail SPF authentication. This is also known as SPF TempError.
DKIM alignment failures
Domain Mismatch: DKIM alignment requires that the d= tag in the DKIM signature (the signing domain) matches or is a subdomain of the From: header domain. If you are using a third-party sender, ensure they are signing with your domain.
Invalid DKIM Signature: Issues like an incorrect public key in DNS, a corrupted signature, or modifications to the email in transit can cause DKIM authentication to fail. Learn why DKIM fails for Outlook.com.
Another frequent cause of rejections, particularly when you first set up DMARC, is deploying a p=reject policy too quickly. While it is the strongest policy for preventing spoofing, it can also lead to legitimate emails being rejected if your SPF and DKIM records aren't perfectly configured for all your sending sources. This is a common reason for DMARC verification failures. Lastly, email forwarding services can sometimes break SPF and DKIM authentication, causing DMARC to fail. This is because the email is modified or re-sent from an intermediate server, which can invalidate the original authentication.
Steps to diagnose and fix
The first critical step in troubleshooting is to examine your DMARC reports. These reports (RUA for aggregate and RUF for forensic) provide invaluable insights into how your emails are authenticating across the internet. They can show you which emails are failing SPF or DKIM, and importantly, which domains are causing these failures. If you're encountering rejections, your reports will likely highlight the specific source that isn't aligning. Here's a typical DMARC record you might have configured:
SPF Verification: Ensure your SPF record includes all legitimate IP addresses and sending services. An SPF record that is too restrictive or includes too many lookups can cause issues. Learn to fix common DMARC issues.
DKIM Validation: Confirm your DKIM record (public key) is correctly published in your DNS and that your sending service is signing emails with the corresponding private key. Check for any errors in the DKIM signature itself. You can find a simple guide to DMARC, SPF, and DKIM to assist you.
If you jumped straight to p=reject, consider reverting to p=none temporarily. This allows you to collect DMARC reports without impacting email deliverability, giving you time to identify and fix all authentication issues. Once your reports show consistent authentication passes, you can gradually move to p=quarantine and then p=reject. Here is how to safely transition your DMARC policy.
Ensuring ongoing deliverability
Implementing DMARC is not a one-time task, especially with stringent recipients like Hotmail. Regular DMARC monitoring is crucial to ensure ongoing compliance and identify any new issues promptly. This includes routinely checking your aggregate reports for authentication trends and any unexpected failures. Monitoring tools can greatly simplify this process.
Component
Role
Impact on Hotmail/Outlook
SPF
Authorizes sending IP addresses for a domain.
Failure can lead to DMARC rejection, especially with strict policies.
DKIM
Digitally signs emails to verify sender identity and message integrity.
Crucial for passing DMARC and avoiding Hotmail spam folders.
DMARC Policy
Tells recipients what to do with emails failing authentication.
A p=reject policy leads to immediate rejection by Hotmail.
Domain Reputation
History of sending behavior, spam complaints, and blacklisting (or blocklisting).
Affects deliverability even with perfect DMARC, particularly to Google and Hotmail.
Even if your DMARC, SPF, and DKIM are perfectly set up, a poor sender reputation can still cause deliverability issues with Hotmail (or any other ISP). Factors like high spam complaint rates, sending to invalid addresses, or being listed on a blacklist (or blocklist) can result in emails landing in spam folders or being rejected. Maintaining a clean email list and engaging content are crucial. It's important to understand why Hotmail might be blocking your emails, even after DMARC setup.
Views from the trenches
Best practices
Always start with a DMARC policy of p=none to gather reports and identify all legitimate sending sources.
Continuously monitor your DMARC aggregate reports to detect any new or unexpected authentication failures.
Ensure both your SPF and DKIM records are correctly configured and pass alignment checks for your sending domains.
Common pitfalls
Implementing a p=reject policy too early without verifying that all legitimate emails pass DMARC.
Ignoring DMARC reports, which contain critical information about your email authentication status.
Not accounting for email forwarding, which can break SPF and DKIM authentication.
Expert tips
Regularly review your email headers for authentication results to pinpoint specific issues causing rejections.
Collaborate with all third-party senders to ensure they support SPF and DKIM authentication for your domain.
Consider using DMARC reporting tools that provide user-friendly dashboards to simplify data analysis.
Expert view
Expert from Email Geeks says: DMARC reports are essential to understand what is not aligning before moving to a reject policy. Without them, diagnosing issues is nearly impossible.
Feb 8, 2024 - Email Geeks
Marketer view
Marketer from Email Geeks says: Ensure you have not jumped straight to a p=reject policy without thoroughly testing and configuring all your email sending sources. This can lead to unexpected rejections.
Feb 8, 2024 - Email Geeks
Restoring Hotmail deliverability
When Hotmail rejects your emails after DMARC setup, the problem almost always lies with SPF or DKIM alignment, or an overly aggressive DMARC policy. The solution involves meticulously checking your authentication records, analyzing DMARC reports, and adopting a phased approach to your DMARC policy implementation. By addressing these core issues, you can significantly improve your email deliverability to Microsoft inboxes.
Remember that DMARC is a powerful tool for email security, but it requires careful implementation and ongoing vigilance. With the right configuration and monitoring, you can ensure your legitimate emails reach Hotmail recipients reliably and securely.
SPF Verification: Ensure your SPF record includes all legitimate IP addresses and sending services. An SPF record that is too restrictive or includes too many lookups can cause issues. Learn to fix common DMARC issues.
Failure can lead to DMARC rejection, especially with strict policies.
A p=reject policy leads to immediate rejection by Hotmail.
Affects deliverability even with perfect DMARC, particularly to Google and Hotmail.
