If you have received a non-delivery report from Microsoft Outlook with error 550 5.4.1 (Recipient address rejected) it is likely you received this message shortly after sending an email to either someone you have already emailed in the past or someone you have just emailed for the first time.
What does error 550 5.4.1 mean?
Error 550 5.4.1 means that fundamentally, there is an issue on either the sending side of the email, the receiving side, or somewhere in the middle (with Microsoft). Where you see the information stating that the address has been rejected, this has been generated from the receiving server, so for what-ever reason, the organisation that is receiving your email, has rejected your email… this may be intentionally, accidentally or temporarily out of your control.
What can the sender do to help resolve this error?
There are a couple of options for you to work through to aid in resolving this issue and I will list them below.
- Just wait. In some instances, you may need to just wait and try again later in the day or the next day. In the instance there is a service outage or the email administrator has made some system changes, this could be the only option. I have detailed in another post how you can view the service health in Exchange Online, Troubleshoot Exchange Online server issues.
- Ensure your DNS records are correct. By this I mean specifically your SPF, DKIM and DMARC records which are there to verify you an authorised sender of your companies domain (ourcloudnetwork.com for example).
- Check your domain status in the Microsoft 365 admin center.
- Log in to the Microsoft 365 admin center
- From the left-hand menu, select domains and ensure the domain is listed as active
- Now go to Admin and select the Exchange admin center
- Click on Mail flow, then Accepted domains
- Confirm that your domain is listed and the domain type for the domain is set to Authoritative or internal relay.
What can the recipient can do to help resolve this error?
If you are an Exchange administrator and your staff has informed you that users are getting a 550 5.4.1 error when people are emailing them, then there are some steps you can take to ensure the issue is remediated on your side.
- Ensure the email address is valid. In some instances, the user may have provided the sender the wrong email address or the email address includes confusing characters such as a capital ‘i’ and lowercase ‘L’. You can use the message trace logs to verify this is the case. See my guide, How to Interpret message trace results and policies in Exchange Online.
- Review your Exchange Transport Rules. If the email address is valid, you may have received some more relevant information from the message trace results, as per the above link. In which, for the next steps you should look at your transport rules. There may likely be a rule which rejects the message based on certain criteria. This will also help the sender resolve any issues if you have taken security measures to reject emails which fail DMARC for example.
- Review your Hybrid Deployment. You may be running a hybrid deployment between on-premise Exchange or another solution. As such, you should review your send connectors and receive connectors for any problems. Follow my guide on How To Validate Connectors In Exchange Online To Resolve Mail Flow Issues.
