554 5.7.1 : Relay access denied

The error message "554 5.7.1 : Relay access denied" typically indicates that the email server is rejecting the attempt to relay the message. This can happen for several reasons, including:

1. Permission Issues: The sender may not have permission to send emails to the recipient, or the recipient may be part of a group that restricts who can send emails to it.
2. Configuration Errors: The email server settings may not be correctly configured to allow relaying from the sender's IP address or domain.
3. Blocked Senders List: The sender's IP address may be on a blocked senders list, preventing the email from being delivered.

To resolve this issue, you can try the following steps:

• Verify that the sender has the necessary permissions to send emails to the recipient.
• Check the email server's configuration to ensure it allows relaying from the sender's domain or IP address.
• If the sender's IP address is blocked, they may need to use the delist portal to request removal from the blocked senders list.

For more detailed troubleshooting steps, you can refer to the relevant Microsoft documentation on handling non-delivery reports (NDRs) and email delivery issues.

References:

• Fix NDR error "550 5.7.1" in Exchange Online
• External senders - Use the delist portal to remove yourself from the blocked senders list and address 5.7.511 Access denied errors

Dear @Terry Tolson,

Thank you for sharing your feedback about your recent interactions with our team. I'm glad that your issue has been solved. Therefore, I would make a brief summary of this post so that other forum members could easily find useful information here:  

Issue Description:

Incoming emails were bouncing back to the sender with the error message “554 5.7.1: Relay access denied”, indicating that the sending server was not permitted to relay messages to the recipient mailbox.

Current Update (confirmed by @Terry Tolson):

The customer confirmed that without making any changes, the issue resolved itself approximately 5 hours later, and email delivery has since returned to normal.

Thank you for your patience and understanding. If you have any further questions or need clarification, please feel free to reach out.

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Dear @Terry Tolson,

Thank you for posting your question in the Microsoft Q&A forum.

The error message "554 5.7.1 Relay Access Denied" usually means that the email server you are trying to send through is blocking your message because it does not recognize you as a legitimate sender.

Generally, the first reason is that your outgoing mail server (SMTP) doesn't allow you to send emails without user authentication. First check your settings in your email application (like Outlook or Thunderbird) to verify that SMTP authentication is enabled.

The other reason is that your email address is marked in spam lists as a source of spam. First check if the email address(es) you are attempting to send the emails to is valid and if there are no spelling mistakes. Secondly, it's possible that your IP address is listed on a real-time blocklist (RBL) that Microsoft Exchange Online Protection uses.

Therefore, here's the Microsoft Official Fixed I recommend you try: Fix NDR error "550 5.7.1" in Exchange Online

If the issue still persists, could you please confirm these questions below to help me narrow down the issue more effectively:

• Can you confirm whether the affected address is a Microsoft 365 business mailbox, a personal Outlook.com/Hotmail account, or a third‑party email account?
• To better understand the scenario, could you confirm whether you’re using the New Outlook or the Classic Outlook client?
• Is the bounce affecting all external senders, or only specific domains or senders?
• Is the recipient mailbox hosted on Microsoft 365 / Exchange Online, or another mail platform?

Note: Please understand that as a forum moderator, my role is to provide general guidance and troubleshooting support. I don’t have access to internal systems or backend tools, and I appreciate your understanding of these limits.

I hope the information shared helps point you in the right direction. Please try the steps above and let me know if they work. If not, we can continue working together to narrow this down.

The first response may not always resolve the issue right away, but with your help and more details, we can work toward a solution.

Thank you for your patience and understanding. I'm looking forward for your reply.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".   

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