Summary
The '550 5.4.1 Recipient address rejected: Access denied AS(xxxx)' error signifies a permanent email delivery failure stemming from the recipient's server. This rejection is usually due to security policies, anti-spam measures, sender reputation issues, or problems with the recipient's address. The 'AS' code often indicates a tenant-level anti-spam block. Common causes include incorrect recipient address, the sender being blacklisted, or misconfigured authentication records (SPF, DKIM, DMARC, and PTR). Resolution involves verifying the recipient's address, ensuring proper sender authentication, checking for blacklisting, reviewing email content for spam triggers, and investigating recipient-side configurations.
Key findings
- Permanent Failure: A 550 error indicates a hard bounce, meaning the email could not be delivered permanently.
- Policy-Based Rejection: The 5.4.1 code typically signifies a policy rejection by the recipient's server, possibly due to anti-spam settings.
- Tenant-Level Blocking: The 'AS' code suggests a block implemented by the tenant's anti-spam measures, not necessarily a global block.
- Authentication Deficiencies: Issues with SPF, DKIM, DMARC, or PTR records can lead to the recipient's server denying access.
- Reputation Concerns: Poor sender reputation or blacklisting of the sending IP/domain can cause rejection.
- Address Validation: The recipient's address itself may be invalid, inactive, or have configuration issues.
Key considerations
- Address Verification: Thoroughly verify the accuracy and validity of the recipient's email address.
- Sender Authentication: Ensure SPF, DKIM, and DMARC records are correctly configured for the sending domain.
- Blacklist Monitoring: Regularly check if the sending IP address or domain is blacklisted using tools like MXToolbox.
- Reputation Management: Monitor sender reputation and take steps to improve it if it is low.
- Content Scrutiny: Review email content for potential spam triggers and ensure adherence to email marketing best practices.
- PTR Record Validation: Ensure the reverse DNS (PTR) record is properly configured to establish server legitimacy.
- Recipient Communication: If feasible, contact the recipient or their email administrator to resolve the issue, especially if the rejection appears unjustified.
- Whitelist Request: Consider requesting to be whitelisted by the recipient's server, particularly for important communications.
What email marketers say
9 marketer opinions
The '550 5.4.1 Recipient address rejected: Access denied AS(xxxx)' error indicates a permanent email delivery failure. This typically means the recipient's server has blocked the email due to security policies, spam filters, or sender reputation issues. Possible causes include an invalid recipient address, the sender's IP or domain being blacklisted, or misconfigured authentication records (SPF, DKIM, DMARC, and PTR). Resolution involves verifying the recipient address, ensuring proper sender authentication, checking for blacklisting, and reviewing email content for spam triggers.
Key opinions
- Hard Bounce: A 550 error signifies a hard bounce, indicating a permanent delivery failure.
- Policy Rejection: The '5.4.1' code often points to a policy rejection by the recipient's server, possibly due to anti-spam measures.
- Authentication Issues: Incorrectly configured SPF, DKIM, DMARC, or PTR records can lead to access denial.
- Reputation Problems: A poor sender reputation or blacklisting of the sending IP/domain can cause rejection.
- Spam Content: Spammy email content can trigger recipient server filters, resulting in a 550 error.
Key considerations
- Recipient Verification: Verify the recipient's email address is correct and active.
- Sender Authentication: Ensure SPF, DKIM, and DMARC records are properly configured for the sending domain.
- Blacklist Checks: Check if the sending IP address or domain is blacklisted using tools like MXToolbox.
- Reputation Monitoring: Monitor sender reputation and take steps to improve it if necessary.
- Content Review: Review email content for potential spam triggers and ensure compliance with email marketing best practices.
- PTR Record: Verify the reverse DNS (PTR) record is correctly configured to improve server legitimacy.
- Contact Recipient: If possible, contact the recipient or their email administrator to resolve the issue, especially if the rejection seems unwarranted.
Marketer view
Email marketer from MXToolbox notes that a 550 error is a permanent rejection. They suggest using MXToolbox's tools to check if the sender's domain or IP is blacklisted and to verify proper DNS records.
17 Jul 2023 - MXToolbox
Marketer view
Email marketer from Sendinblue answers that a 5.4.1 error usually means the destination address rejected the message. The sender may need to contact the recipient by another means to resolve the issue or to confirm the email address.
2 Sep 2024 - Sendinblue
What the experts say
2 expert opinions
The '550 5.4.1 Recipient address rejected: Access denied,' particularly with the 'AS' code, is a permanent failure indicating a policy rejection by the recipient's mail server, likely due to tenant-level anti-spam measures rather than a simple 'no such user' error.
Key opinions
- Permanent Failure: 5xx errors are categorized as permanent failures, preventing email delivery.
- Policy Rejection: The 5.4.1 code suggests the recipient's server actively rejects the email based on pre-defined policies.
- Anti-Spam Block: The 'AS' code strengthens the likelihood of an anti-spam policy causing the rejection.
- Tenant-Level Block: The block is often implemented at the tenant level by the recipient, not necessarily by a global provider like Microsoft.
Key considerations
- Investigate Recipient Policies: Understanding the recipient's specific anti-spam policies is crucial.
- Review Sending Practices: Evaluate sending practices to ensure compliance with anti-spam guidelines and avoid triggering filters.
- Authenticate Email: Properly configure SPF, DKIM, and DMARC to enhance sender credibility.
- Monitor Reputation: Maintain a good sender reputation to minimize the chances of being flagged as spam.
Expert view
Expert from Email Geeks explains that the "550 5.4.1 Recipient address rejected: Access denied" error, especially with the 'AS' code, often indicates a block implemented by the tenant's anti-spam measures, rather than a simple 'no such user' error.
10 Jul 2023 - Email Geeks
Expert view
Expert from Word to the Wise explains that 5xx errors are permanent failures. A 5.4.1 code generally indicates a policy rejection and means the mail server will not send the message. In cases with the AS code, this is more likely to be an anti-spam policy block.
28 Nov 2022 - Word to the Wise
What the documentation says
5 technical articles
The '550 5.4.1 Recipient address rejected: Access denied' error indicates a permanent rejection of the email by the recipient's server, often due to security policies, filtering, or issues with the recipient address itself. Potential causes include incorrect recipient address, sender being blocked, SPF record issues, or general email configuration problems. Resolution involves verifying the recipient address, checking sender reputation, ensuring proper email authentication (SPF), and investigating server configurations.
Key findings
- Permanent Rejection: 5xx errors, including 550, represent permanent failures in email delivery.
- Security Policies: Recipient server's security policies and filtering are often the root cause.
- Address Validity: The recipient's email address may be invalid or have issues.
- Authentication Problems: Incorrect or missing SPF records can trigger the error.
- Configuration Issues: Incorrect email configurations on either the sender or receiver side can lead to the error.
Key considerations
- Address Verification: Thoroughly verify the recipient's email address for accuracy.
- Reputation Check: Check the sender's IP address and domain reputation to identify potential blacklisting.
- Authentication Setup: Ensure proper SPF records are in place to authenticate the sender's domain.
- Configuration Review: Review email server configurations to identify and correct any issues.
- Support Contact: Consider contacting recipient support or whitelisting the sender if the issue persists.
Technical article
Documentation from RFC 3463, which defines enhanced mail system status codes, explains that a 5.4.1 status code generally signifies a problem with the destination email address. The sending system may need to verify the validity of the recipient address.
16 Sep 2024 - RFC Editor
Technical article
Documentation from Microsoft Support explains that the '550 5.4.1 Recipient address rejected: Access denied' error indicates that the recipient's email server has rejected the message due to security policies or filtering. It suggests checking the sender's IP address and domain reputation to ensure they are not blacklisted.
17 Oct 2022 - Microsoft Support
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