--- title: "How to fix “550; 5.7.15 Access Denied” rejections? | AutoSPF" description: "Microsoft has always prioritized email security, and in pursuit of this goal, it mandated that all bulk senders properly authenticate their messages." image: "https://autospf.com/og/blog/how-to-fix-550-5-7-15-access-denied-rejections.png" canonical: "https://autospf.com/blog/how-to-fix-550-5-7-15-access-denied-rejections/" --- Quick Answer Microsoft has always prioritized email security, and in pursuit of this goal, it mandated that all bulk senders properly authenticate their messages. This means that anyone sending over 5,000 emails daily to Outlook, Hotmail, and other Microsoft consumer mailboxes must have properly configured SPF, DKIM, and DMARC records in place. If a bulk sender fails to do so, a “550; How to fix “550; 5.7.15 Access Denied” rejections? Your browser does not support the audio element. [ Download episode](/audio/how-to-fix-550-5-7-15-access-denied-rejections.mp3) Share [ ](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fautospf.com%2Fblog%2Fhow-to-fix-550-5-7-15-access-denied-rejections%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=How%20to%20fix%20%E2%80%9C550%3B%205.7.15%20Access%20Denied%E2%80%9D%20rejections%3F&url=https%3A%2F%2Fautospf.com%2Fblog%2Fhow-to-fix-550-5-7-15-access-denied-rejections%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fautospf.com%2Fblog%2Fhow-to-fix-550-5-7-15-access-denied-rejections%2F "Share on Facebook") [ ](https://reddit.com/submit?url=https%3A%2F%2Fautospf.com%2Fblog%2Fhow-to-fix-550-5-7-15-access-denied-rejections%2F&title=How%20to%20fix%20%E2%80%9C550%3B%205.7.15%20Access%20Denied%E2%80%9D%20rejections%3F "Share on Reddit") [ ](mailto:?subject=How%20to%20fix%20%E2%80%9C550%3B%205.7.15%20Access%20Denied%E2%80%9D%20rejections%3F&body=Check out this article: https%3A%2F%2Fautospf.com%2Fblog%2Fhow-to-fix-550-5-7-15-access-denied-rejections%2F "Share via Email") ![Access Denied](https://media.mailhop.org/autospf/images/2025/06/spf-flattening-5608.jpg) Microsoft has always prioritized [email security](/), and in pursuit of this goal, it mandated that all bulk senders properly authenticate their messages. This means that anyone sending over 5,000 emails daily to Outlook, Hotmail, and other Microsoft consumer mailboxes must have properly configured SPF, [DKIM](/10-reasons-for-regular-spf-record-checks-in-cybersecurity/dkim-record-check/), and DMARC records in place. If a bulk sender fails to do so, a “550; 5.7.15 Access Denied” error will be triggered, leading to complicated email delivery issues. For a complete walkthrough of every SPF error type, see our [SPF Errors and Troubleshooting Guide](/blog/spf-errors-troubleshooting-guide/). ## What is the ‘550; 5.7.15 Access Denied’ error code? ‘[550; 5.7.15 Access Denied](https://cybersecuritynews.com/microsoft-to-block-emails/)’ is a permanent rejection error that recipients hit when their emails fail to get delivered to a Microsoft consumer mailbox. Here are the two possible reasons for this error- ### 1\. Missing authentication protocols _It is compulsory for high-volume email sending domains to have SPF, DKIM, and DMARC in place_. ![Sender Policy Framework ](https://media.mailhop.org/autospf/images/2025/06/spf-record-syntax-8074.jpg) #### SPF [SPF](/blog/what-is-spf-email-a-guide-to-sender-validation-technology/) is short for Sender Policy Framework - the oldest email authentication protocol. It prevents [malicious actors](https://www.securitymagazine.com/articles/100953-new-research-malicious-actors-are-imitating-tech-companies) from sending spam and impersonated emails on your behalf. It works by allowing domain owners to publish a list of authorized mail servers in their [DNS records](https://www.cloudflare.com/learning/dns/dns-records/). When an email is received, the recipient’s mail server checks the SPF record of the sender’s domain to verify if the email came from an approved server. If it doesn’t match, the email may be marked as spam or rejected entirely. SPF helps improve [email deliverability](/blog/brevo-spf-record-a-complete-guide-to-optimize-email-deliverability/) and protects against spoofing and phishing attacks that exploit fake sender identities. #### DKIM _DKIM stands for DomainKeys Identified Mail, a method that helps verify if an email is actually sent from the claimed domain_. DKIM operates on the basis of a digital signature that is attached to the outgoing [email’s header](https://proton.me/blog/what-are-email-headers). This signature is created using the sender’s [private key](https://www.techtarget.com/searchsecurity/definition/private-key). When the email reaches the recipient’s server, it retrieves the sender’s [public key](https://www.techtarget.com/searchsecurity/definition/public-key) from the domain’s DNS records to validate the signature. If the content or sender information has been tampered with, the verification fails. DKIM helps prevent spoofing and ensures the message hasn’t been altered during transit, boosting email integrity and deliverability. #### DMARC DMARC is short for Domain-based Message Authentication, Reporting, and Conformance. It is a contemporary email authentication protocol that is based on SPF and DKIM. DMARC instructs the receiving server on how to manage illegitimate emails sent from your domain - take no action, [mark as spam](https://pressgazette.co.uk/publishers/digital-journalism/facebook-spam-posts-independent-small-news-publishers/), or deny entry altogether. ![email spoofing](https://media.mailhop.org/autospf/images/2025/06/spf-flattening-3047.jpg) ### 2\. Alignment issues You can experience the ‘550; 5.7.15 Access Denied’ error if your [email authentication](/blog/role-relevance-of-dns-spf-records-for-email-authentication/) protocols aren’t in proper alignment. As per Microsoft’s new rules for high-volume senders, SPF and DKIM must pass for the sending server, and DMARC must align with SPF or DKIM (preferably both)_._ ## How Do You Fix the ‘550; 5.7.15 Access Denied’ error? If you are a bulk sender and you are facing this issue, then here are the ways to fix it- ![email authentication ](https://media.mailhop.org/autospf/images/2025/06/spf-record-tester-5079.jpg) ### 1\. Enable SPF List down all the IP addresses and [mail servers](https://www.activecampaign.com/glossary/mail-server) that send emails from your domain, and then create an SPF record using an online [SPF generator](/spf-validator/spf-generator/) tool. Use the Soft Fail mechanism (indicated by \~all) to instruct the receiving server to mark unauthorized emails as spam. Use the Hard Fail mechanism (indicated by -all) to have them rejected outright. ### 2\. Enable DKIM Use a credible DKIM generator tool to create an error-free DNS record and publish it on your domain so that all the outgoing emails can be evaluated for their integrity. ![spam or junk folder ](https://media.mailhop.org/autospf/images/2025/06/spf-validator-2204.jpg) ### 3\. Configure DMARC After enabling SPF and DKIM, create a DMARC record and choose the appropriate policy. - p=none: This policy only monitors email traffic without enforcing any action. _It helps domain owners analyze who is sending emails on their behalf and is Ideal for the first stage of DMARC implementation_. - p=quarantine: This policy tells recipients to treat unauthenticated emails with suspicion. Such emails may be sent to the [spam or junk folder](https://cybernews.com/news/microsofts-breach-notification-emails-end-up-in-spam-folder/). It’s a middle-ground approach to gradually move toward full protection. - p=reject: It’s the strictest DMARC policy, under which the unauthenticated emails are outright blocked. It offers the highest protection against [spoofing and phishing](https://www.msspalert.com/brief/novel-usps-spoofing-phishing-attack-relies-on-malicious-pdfs). Best used once you’re confident all [legitimate sources](https://www.forbes.com/sites/petersuciu/2024/12/04/elon-musk-claims-x-is-a-legitimate-source-for-news-can-it-be-trusted/) are properly authenticated. ![DKIM helps prevent spoofing ](https://media.mailhop.org/autospf/images/2025/06/spf-record-example-6041.jpg) ### 4\. Evaluate DMARC reports Evaluating DMARC reports helps identify which email sources are failing SPF or DKIM alignment and causing Microsoft’s ‘550 5.7.15 Access Denied’ error. By reviewing DMARC aggregate reports, you can: - Spot unauthorized sources attempting to send on your domain’s behalf. - Detect legitimate services (like [CRMs](https://www.ibm.com/think/topics/crm) or marketing tools) that aren’t correctly configured. - _Pinpoint which messages are failing DMARC and why - whether due to SPF, DKIM, or misalignment._ Once identified, you can fix these misconfigurations and restore deliverability. So, all in all, email authentication is taking the center stage. If your domain still lacks SPF, DKIM, and [DMARC](https://dmarcreport.com/dmarc-fundamentals/what-is-dmarc/), reach out to us. We are experts in deploying and reconfiguring these protocols. ## Topics [ DKIM ](/tags/dkim/)[ DMARC ](/tags/dmarc/)[ email security ](/tags/email-security/)[ SPF ](/tags/spf/)[ SPF record ](/tags/spf-record/) ![Vishal Lamba](https://media.mailhop.org/autospf/images/authors/vishal-lamba.jpg) [ Vishal Lamba ](/authors/vishal-lamba/) Content Specialist Content Specialist at AutoSPF. Writes vendor-specific SPF configuration guides and troubleshooting walkthroughs. [LinkedIn Profile →](https://www.linkedin.com/in/vishal-lamba/) ## Ready to get started? Try AutoSPF free — no credit card required. [ Book a Demo ](/book-a-demo/) ## Related Articles [ Intermediate 3m 3 points to consider before setting your SPF record to -all (HardFail) May 22, 2025 ](/blog/3-points-to-consider-before-setting-your-spf-record-hardfail/)[ Intermediate 5m Are Your SPF and DKIM Identifiers Aligned? Jul 18, 2024 ](/blog/are-your-spf-and-dkim-identifiers-aligned/)[ Intermediate 6m Automated Solutions for Preventing Email Spoofing May 7, 2026 ](/blog/automated-solutions-for-preventing-email-spoofing/)[ Intermediate 7m AutoSPF Explains: The Definitive Guide to Adding an SPF Record to Cloudflare Jan 7, 2026 ](/blog/autospf-definitive-guide-adding-spf-record-cloudflare/) ```json {"@context":"https://schema.org","@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com","logo":{"@type":"ImageObject","url":"https://autospf.com/images/autospf-logo.png"},"description":"Automatic SPF flattening and email authentication management. 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