Fix email delivery issues for error code 550 5.4.1 in Office 365

Here’s what to do if you get delivery status notification (DSN) error code 5.4.1 or Exchange NDR 5.4.1 in a non-delivery report (NDR). There can be several causes for dsn error code 5.4.1, but this might happen if you send email and the outbound connection attempt was not answered.

Button to get email user help Button to get admin help

Use the information in the Exchange NDR to decide how to fix the problem. More causes and solutions for the outbound connection attempt not answered are provided later in this topic.

Email user help to fix the problem that is causing Exchange NDR 5.4.1

Message delivery from server-to-server can be complicated or require special access to settings, so most of this topic is designed for an Office 365 email administrator and not the average email sender. If the steps here don’t help, contact your email administrator and refer them to this information so they can try to resolve the issue for you.

Just wait.   - It may seem strange but this error may go away on its own after a few days. If the person managing your Office 365 account or your email server settings decides to make a change to the domain name system (DNS) records, this can prevent you from sending and receiving email for a brief period, even if they did everything correctly. It can take up to 72 hours for some changes to propagate to all DNS servers on the Internet. If you'd like more details about DNS records, see DNS basics.

There could also be an issue with the Office 365 service that is causing the problem. The average email user can't do anything about this except wait for it to be resolved.

Admin help for NDR 5.4.1, outbound connection attempt was not answered

Most of the following procedures for Office 365 email administrators require special access to settings. If you are an admin, try the steps here in order to help your users send and receive messages successfully.

Incorrect MX record

If external senders receive this NDR when they send mail to recipients in your domain, try the solutions described in this section.

The mail exchange (MX) record for your domain may be incorrect. For example, it may be pointing to an invalid mail server. Check with your domain registrar or DNS hosting service to verify the MX record for your domain is correct. The MX record for a domain that's enrolled in Exchange Online uses the syntax <domain>

Also, verify you have only one MX record configured for your domain. Using more than one MX record for a domain that's enrolled in Exchange Online isn't supported.

You can test your MX record and your ability to send mail from your Exchange Online organization by using the Verify MX Record and Outbound Connector Test at Office 365 > Mail Flow Configuration in the Microsoft Remote Connectivity Analyzer

Domain configuration issues

If external senders receive NDR 5.4.1 when they send mail to recipients in your domain, try these steps.

  1. Open the Office 365 portal at

  2. Click Domains and verify your domain appears in the list as Active.

  3. Select the domain and click Troubleshoot. Follow the troubleshooting wizard steps.

If you maintain control of the DNS records for your Office 365 domain, you can also check the status of the domain in the Exchange admin center by performing these steps:

  1. Open the Office 365 portal, click Admin, and select Exchange.

  2. Click Mail flow > Accepted domains.

  3. Verify that your domain is listed, and verify the Domain Type value for the domain. Typically, the Domain Type value should be Authoritative. However, if you have properly configured a shared domain, the value may be Internal Relay.

Updated DNS records haven't propagated

You updated your domain's DNS records correctly for Office 365, but the changes haven't propagated to all DNS servers on the Internet. Changes to your domain's DNS records may take up to 72 hours to propagate to all DNS servers on the Internet.

Hybrid deployment configuration issues

If your domain is part of a hybrid deployment between Exchange and Exchange Online, check the following items:

  • Verify the configuration of the Send and Receive connectors in your on-premises Exchange organization that are used for hybrid. These connectors are configured automatically by the Hybrid Configuration Wizard, and the wizard may need to be run again by your Exchange administrator.

For more information, see Microsoft Knowledge Base article KB2827473.

For more information about transport routing in hybrid deployments, see Transport Routing in Exchange 2013 Hybrid Deployments.

Service issues in Exchange Online

A service issue in Office 365 may be causing the problem. To check the status of Office 365, perform the following steps:

  1. Open the Office 365 portal at

  2. Click Service health to see an overview of any issues.

  3. Select View all to a get more details about all known issues.

What happened to cause error code 5.4.1 and what does this error mean?

The mail server that's generating the error doesn't accept mail for the recipient's domain. This error is generally caused by mail server or DNS misconfiguration.

Details about this NDR

The Exchange Online non-delivery report (NDR) notification for this specific error may contain some or all of the following information:

  • User information section   

    • Relay Access Denied

    • The outbound connection attempt was not answered because either the remote system was busy or it was unable to take delivery of the message.

  • Diagnostic information for administrators section   

    • No answer from host.

    • #550 5.4.1 Relay Access Denied ##

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See Also

What are Exchange NDRs in Exchange Online and Office 365

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