Why does my email header show DKIM and SPF as none, and how do I fix Outlook deliverability issues?
Matthew Whittaker
Co-founder & CTO, Suped
Published 19 Apr 2025
Updated 17 Aug 2025
7 min read
It is a common and incredibly frustrating scenario: you send an email, check the header, and see "DKIM: none" or "SPF: none." Yet, when you run tests on your domain, everything comes back as "pass." This disparity is a key reason why your emails might be landing in spam folders, especially with major providers like Outlook (or Microsoft 365).
Email authentication protocols like SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) are foundational to email security. When headers show "none," it means the recipient's mail server could not verify the sender's authenticity through these critical methods. This immediately raises red flags, leading to severe deliverability issues and often prevents your messages from reaching the inbox.
When your email header displays DKIM=none or SPF=none, it indicates that the receiving mail server, such as Outlook, was unable to find or validate the corresponding authentication records for your sending domain. This often happens despite independent testing tools showing a "pass" result, which can be confusing and lead to questions about what is truly happening.
One common reason for this discrepancy is that email headers are read sequentially, and sometimes an intermediary server or forwarding rule can strip or modify authentication results before the email reaches the final destination. Another factor might be temporary DNS lookup errors on the recipient's side, or your DNS records might not have fully propagated globally. This is especially true when dealing with different mailbox providers, as their parsing mechanisms can vary.
An SPF=none outcome suggests that the receiving server found no SPF record for the sending domain, or that the record was improperly formatted. Similarly, DKIM=none means the server could not find a valid DKIM signature or public key. Both scenarios severely impact trust and often result in messages being sent to the junk or spam folder. You can gain more insight on general authentication issues by reviewing email problems.
Example email header showing SPF and DKIM as 'none'plaintext
Authentication-Results: spf=none (sender IP is 192.0.2.1) smtp.mailfrom=example.com; dkim=none (message not signed) header.d=example.com;
Received-SPF: None (protection.outlook.com: example.com does not designate permitted sender hosts)
Diagnosing authentication failures
The first step in diagnosing why your SPF or DKIM is showing 'none' is to meticulously examine the raw email headers. These headers provide a detailed log of every server the email traversed and the authentication results at each step. Looking at the Authentication-Results header will often reveal exactly where the failure occurred. Understanding how to check these results is key, as demonstrated in discussions about Gmail SPF/DKIM issues.
You should also use online tools to check your domain's SPF and DKIM records directly from a DNS perspective. This helps confirm that your records are published correctly and are accessible globally. However, even if these tools show 'pass', remember that the actual email path and the recipient's server interpretation are what truly matter. For common issues with Microsoft Outlook, remember that specific troubleshooting steps may be required.
A crucial element often overlooked is alignment. While SPF and DKIM might pass independently, DMARC (Domain-based Message Authentication, Reporting & Conformance) requires that the domain in your 'From:' header (RFC 5322.From) aligns with the domains used for SPF or DKIM. If there's a misalignment, even with passing SPF and DKIM, the DMARC check can fail, leading to mail being rejected or quarantined. This is a frequent cause of emails going to spam or the junk folder. You can learn more about this in our guide on why emails go to spam.
Problem
Incorrect DNS records: SPF or DKIM records contain typos or invalid syntax, making them unreadable by mail servers.
Missing records: SPF or DKIM records are not published in DNS for the sending domain at all.
DNS propagation delays: Newly published records haven't updated across global DNS servers, taking time to take effect.
Multiple SPF records: Having more than one SPF TXT record for a domain can invalidate SPF checks entirely.
RFC 5322.From domain mismatch: The domain in the "From:" header does not align with the SPF or DKIM authenticated domain, causing DMARC to fail.
Solution
Validate syntax: Use a DNS checker to verify record syntax and ensure no errors exist.
Publish missing records: Add the necessary TXT records for SPF and DKIM through your domain registrar.
Wait for propagation: Allow up to 48 hours for DNS changes to fully propagate globally.
Merge SPF records: Combine multiple SPF records into a single, comprehensive record to prevent validation issues.
Ensure DMARC alignment: Configure SPF and DKIM to authenticate the RFC 5322.From domain, which is crucial for DMARC to pass.
Fixing Outlook deliverability issues
To resolve DKIM=none or SPF=none and improve Outlook deliverability, begin by ensuring your DNS records for SPF and DKIM are flawlessly configured. For SPF, verify that all legitimate sending sources are included in your record and that you don't exceed the 10 DNS lookup limit. If your emails use multiple services, merging SPF records is essential to prevent common errors like the hidden SPF DNS timeout.
For DKIM, ensure your public key is correctly published in your DNS and matches the private key used by your sending service. A common issue leading to DKIM=none (or "message not signed") is a missing or misconfigured public key. If your domain is hosted on Microsoft 365, there are specific steps for troubleshooting authentication failures.
Beyond direct SPF and DKIM configuration, focus on DMARC implementation. Even with p=none initially, DMARC provides valuable reports that show authentication failures and alignment issues. Microsoft (and Google) increasingly rely on DMARC to determine email legitimacy. Consistent DMARC passing, including alignment, significantly boosts your sender reputation and inbox placement, especially with major email providers. Being on an email blocklist (or blacklist) can also severely impact your deliverability, pushing messages to spam folders or leading to outright rejection. Understanding why your emails are having deliverability issues can lead to better outcomes.
Outlook deliverability best practices
Achieving good email deliverability to Outlook inboxes requires attention to technical details and sender reputation. Staying compliant with their requirements is critical.
Implement DMARC: Even with a relaxed policy (p=none), DMARC provides crucial insights into authentication failures through reports.
Monitor authentication reports: Regularly review DMARC reports to identify and resolve SPF and DKIM failures promptly.
Maintain sender reputation: Avoid sending to invalid addresses and manage bounce rates effectively to keep your reputation high.
Monitor blocklists: Regularly check if your sending IP or domain is listed on any email blocklists (or blacklists).
Advanced troubleshooting for Microsoft environments
Microsoft's policies for email authentication, especially for Outlook.com and Microsoft 365 users, are becoming stricter. They place significant emphasis on both SPF and DKIM passing, along with DMARC alignment. You might find that even if your authentication passes for other providers, it fails with Microsoft, sometimes due to issues like DKIM failures specifically with Microsoft.
One particular challenge with Outlook (Microsoft) can be related to how they handle email forwarding. When an email is forwarded, the authentication results can be altered or invalidated, leading to SPF=fail or DKIM=fail on the final hop. This can cause legitimate emails to be marked as spam or lead to DKIM body hash errors. Understanding these nuances is crucial for improving your deliverability with Microsoft services.
Proactive monitoring of your email deliverability is key. Regularly check your DMARC reports to identify consistent failures or 'none' results and address them promptly. Staying informed about Microsoft's evolving sender requirements, like those detailed by Spam Resource on their blog, helps you adapt your email infrastructure before issues impact your campaigns. This can help prevent your emails from facing deliverability issues with Outlook.
Views from the trenches
Best practices
Ensure DNS changes have fully propagated before re-testing authentication, as this can take up to 48 hours.
Consistently monitor DMARC reports for authentication failures, which pinpoint issues that tools might miss.
Verify that your sending domain's RFC 5322.From header aligns with SPF or DKIM authenticated domains to ensure DMARC compliance.
Implement a DMARC policy, even if it starts with 'p=none', to gather crucial insights into your email authentication.
Common pitfalls
Expecting immediate authentication success after DNS changes, without accounting for propagation delays.
Overlooking DMARC alignment issues, where SPF and DKIM pass, but the 'From:' domain does not match.
Relying solely on external testing tools without reviewing raw email headers for actual recipient authentication results.
Using email warming services that often lack deliverability best practices and can be ineffective.
Expert tips
Check for intermediary mail server modifications in headers that might strip or alter authentication results.
Understand that Microsoft's internal mail routing can sometimes show 'none' initially, even if authentication passes later.
Be aware that email forwarding can break SPF and DKIM authentication, leading to unexpected delivery issues.
Always include all legitimate sending IPs and services in your SPF record to prevent soft fails or rejections.
Expert view
Expert from Email Geeks says: Ensure you are configuring DKIM and DMARC for robust email authentication, as these protocols are vital for modern email deliverability.
2024-04-11 - Email Geeks
Expert view
Expert from Email Geeks says: Sometimes, intermediate Microsoft mail servers can modify headers, which might result in authentication results showing as 'none' initially, even if they pass later in the chain. Also, be wary of email warming services as they often do not align with deliverability best practices.
2024-04-12 - Email Geeks
Ensuring your emails reach the inbox
Seeing DKIM=none or SPF=none in your email headers, especially when targeting Outlook recipients, signals a critical issue with your email authentication. These 'none' statuses undermine trust and can severely impact your deliverability, causing messages to land in spam or be outright rejected. Fixing these issues is paramount to ensuring your emails reach their intended destination and avoid being flagged as spam.
By diligently configuring your SPF, DKIM, and DMARC records, regularly checking your email headers, and understanding the specific requirements of major mailbox providers like Microsoft, you can resolve these authentication failures. A robust authentication setup is the cornerstone of successful email deliverability and ensures your messages are trusted and delivered.
Google) increasingly rely on DMARC to determine email legitimacy. Consistent DMARC passing, including alignment, significantly boosts your sender reputation and inbox placement, especially with major email providers. Being on an email blocklist (or blacklist) can also severely impact your deliverability, pushing messages to spam folders or leading to outright rejection. Understanding why your emails are having deliverability issues can lead to better outcomes.
Outlook inboxes requires attention to technical details and sender reputation. Staying compliant with their requirements is critical.
