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How to Troubleshoot the "550 5.0.1 Recipient Rejected" Error

Summary: This article provides guidance on how to resolve email delivery issues, specifically addressing the "550 5.0.1 Recipient rejected" error and steps to take when emails are not being delivered.

Understanding Email Delivery Issues

When sending emails, you may encounter delivery issues that prevent your messages from reaching the intended recipient. One common error is the "550 5.0.1 Recipient rejected" error, which indicates that the recipient's email address is invalid or does not exist.

Causes of the "550 5.0.1 Recipient Rejected" Error

This error can arise due to several reasons:

  • The recipient's email address may not exist.
  • There may be spelling mistakes in the email address.
  • The email address may have been incorrectly entered due to auto-complete suggestions.
  • The recipient's email server could be down or unreachable.
  • The recipient's domain may be blocked by the sender's email server.
  • The recipient's mailbox may be full.

Steps to Resolve Email Delivery Issues

If you encounter the "550 5.0.1 Recipient rejected" error, follow these steps to troubleshoot and resolve the issue:

  1. Verify the Email Address:

    • Double-check the recipient's email address for any spelling errors.
    • Ensure that you are not using an outdated address from your contacts.

  2. Manually Enter the Email Address:

    • Remove the recipient's email address from your auto-complete list.
    • Type the email address manually to avoid any auto-complete errors.

  3. Check Recipient's Email Status:

    • Contact the recipient (via phone or another method) to confirm that their email address is valid and active.
    • Ask if they have any email forwarding rules that might be misconfigured.

  4. Review Bounce Status:

    • If the email address has previously bounced, it may be flagged in your email service provider's system (e.g., SendGrid).
    • Request your email service provider to remove the email address from the bounce list if it is valid.

  5. Resend the Email:

    • After verifying and correcting the email address, attempt to resend the email.

Additional Considerations for Email Administrators

If you are an email administrator and continue to experience issues, consider the following:

  • Confirm Email Address Validity: Ensure that the recipient's email address exists and is configured to accept messages.
  • Directory Synchronization: If using a hybrid environment, verify that the recipient's email address is correctly synchronized between Office 365 and your on-premises directory.
  • Check Forwarding Rules: Investigate any forwarding rules that may be incorrectly set up, either by the recipient or through mail flow rules.
  • License Verification: Ensure that the recipient has a valid Office 365 license assigned.

Conclusion

Resolving email delivery issues, particularly the "550 5.0.1 Recipient rejected" error, involves verifying the recipient's email address and ensuring that it is correctly entered and active. By following the outlined steps, you can effectively troubleshoot and resolve common email delivery problems. If issues persist, further investigation may be required by your email administrator or service provider.