Error 550 5.7.1 Unable to Relay Exchange 2016

Tej Pratap Shukla | Modified: February 11, 2021 | Exchange Server, General Exchange Issue | 4 Minutes Reading

In this Article write up we are going to discuss about Error 550 5.7.1 Unable to Relay Exchange 2016 & 2010. Many times this error is faced by Exchange Administrators therefore I am going to write a solution to the error. Many Exchange Administrators Configure the receive connectors during the installation time of the Exchange Server.

How to Identify Unable to Relay Error?

You will ger Error code 550 5.7.1, 5.0.0, 5.7.3 and 501 5.7.1, all these codes identify unable to relay error. Another identification method can be that when you see lot of mails in waiting in sending queue.

Cause of Error 550 5.7.1 Unable to Relay

There are following reasons which may lead to the error:

When Email couldn’t deliver to receiver mailbox.
When receiver server does not support relay for receiving mails or we can say that the receiver server have restricted send’s domain.
Another reason could be mailbox corruption of exchange server.

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Fix Error 550 5.7.1 Unable to Relay

Now I am about to describe the solution to fix the error Error 550 5.7.1 Unable to Relay for Exchange server 2016, 2013, 2010, 2007, & 2003. You have to allow relay access permissions for all recipients in exchange server.

Fix Error in Exchange Server 2016

In Exchange 2016, we have to first create New Receive Connector in Exchange Server. Just run below written command in Exchange Management Shell (EMS) for creating new receive connector.
New-ReceiveConnector -Name 'rconnect' -Usage 'Custom' -Bindings '10.12.12.1' -Fqdn 'win10.mailtest.com' -RemoteIPRanges '0.0.0.0-255.255.255.255' -Server 'Win10'
In above command:
rconnect is new receive connector name
Custom is type of usage
Next to Bindings, IP address is written
win10.mailtest.com is Fully Qualified Domain
Next to RemoteIPRanges, dynamic range of IP address is written
Win10 is Server Name.
After Successful execution of above command the New Receive Connector will be created with the name of rconnect.

Now we have to add permissions to Access Control List of Receive Connector which will allow anonymous users to access the relay of receive connector. And user will not get Error 550.5.7.1 Unable to Relay.

Run Below written command in Shell to add the permission:
Get-ReceiveConnector "rconnect" | Add-ADPermission -User "NT AUTHORITY\ANONYMOUS LOGON" -ExtendedRights "ms-Exch-SMTP-Accept-Any-Recipient"
Where:
rconnect is receive connector name
NT AUTHORITY\ANONYMOUS LOGON is anonymous user which is same by default.
You can also run the above written command for add permissions for anonymous user in already configured receive connectors.

Fix Error in Exchange Server 2010

In Exchange 2010 first Create a New Recieve connector in Exchange Server.

Go to Exchange Management console (EMC) through Start Menu.
In EMC expend Microsoft Exchange On-Permises and then Expand Server Configurations and then click on Hub Transport.
Now at right side in Action Pane click on New Receive Connector.
Now you will see new receive connector wizard. Just enter New Name of Receive connector in Name text box and hit Next button.
Now Check the Port Number and Enter Fully Qulified Domain Name (FQDN) and hit Next button.
Now check the IP address or you can enter new IP address by clicking on + button. After entering the IP address hit Next button to proceed.
Now hit New button for creating new Receive Connector.

Now After successful Creation of new Receive Connector we have to add permissions for anonymous users. in Access Control List (ACL). Therefore, just run below written command. After execution of this command the Access Control List would be configured to relay access for anonymous users.

Get-ReceiveConnector "rconnect" | Add-ADPermission -User "NT AUTHORITY\ANONYMOUS LOGON" -ExtendedRights "ms-Exch-SMTP-Accept-Any-Recipient"
After Execution of the above written command, the “error 550 5.7.1” Unable to relay will be resolved.

Conclusion

In this article we discussed about how to resolve the error 550 5.7.1 Unable to relay. We discussed the reason of occurrence of this error and the way to resolve it. I have created a new receive connector for demonstration in Exchange server 2016 & 2010. I have described both way using Exchange Management Shell Commands in case of Exchange 2016 and Using Exchange Management Console in case of Exchange 2010. And after creation of New receive connector, I have executed the shell commands for assigning anonymous permissions to Receive Connector. Exchange Admin can also execute this command for already configured receive connectors.
At last we can say that the error can be resolved be adding permissions to receive connectors.