How to Fix Exchange SMTP Error 550 5.7 1 Unable to Relay?

With Simple Mail Transfer Protocol SMTP, emails are transferred from an email client to the server using Port 25. However, it can sometimes cause problems and show the error message “Fix Exchange SMTP Error 550 5.7.1 Unable to Relay.” Let’s look at what Exchange SMTP error 550 5.7.1 is and how to fix it so that you can access your emails again.

SMTP Error 550 5.7.1 Unable to Relay: What Does It Mean?

Exchange SMTP Error 550 5.7.1 Unable to Relay is an HTTP Protocol error code. This message essentially serves as a non-delivery report for emails relayed via Microsoft Exchange Server. Because of this error user can face problems while sending emails between Exchange Server and its client application.

Reasons of SMTP error code 550 5.7.1?

The error Exchange SMTP error 550 Unable to relay error can be occur by a number of factors. There are the following:-

  • Authentication failed or the recipient does not have permission to receive messages
  • The Outgoing Mail Server does not recognize the sender address.
  • Exchange database corruption.
  • The email was forwarded to the incorrect server.
  • Sending an email to a wide number of people

How to Fix SMTP Error 550 5.7.1 ‘Unable to Relay’ in Exchange?

Note:- We’ve mentioned a few manual solutions for Exchange Error 550 5.7.1 below. To run the commands and steps outlined below, you’ll need administrator access and permissions.

Method 1:- Fix SMTP Error 550 5.7.1 with Exchange Server Manager

  • Start the Exchange Server Manager on your computer.
  • Go to the Administrative Groups section.
  • Navigate to Administrative Group Name>>Server>>Server Name from the Administrative Groups section.
  • Hit the Protocols option under your Server Name and select SMTP.
  • Right-click the Default SMTP Virtual Server option and select Properties.
  • Then, on the Access tab, select the Relay option and Only The List Below.
  • Choose the IP address and domain that you want to relay.
  • Select “Allow all computers which successfully authenticate to relay regardless of the list above“.
  • Close all opened tabs. And after this you can also send emails using the SMTP Server.

Method 2:- Repair Exchange Databa

There is no need to go to any other opt solution if you have fixed the problem by using the above-provided method. However, if anything continues to go wrong, the most likely cause is corruption in the Exchange database file.

The Exmerge utility will resolve this, but it needs a technical expert to complete the process. In order to prevent data loss in the event of extreme corruption, it is often preferable to use specialist Exchange recovery tools. So the user can recover significant corruption from an offline/dismounted EDB file using the eSoftTools Exchange Server Database Recovery tool.


This Exchange recovery program recovers all data from corrupted Exchange EDB files, extracts mailboxes, and saves them as PST files with no data loss. It also aids Exchange administrators in recovering and restoring deleted mailboxes from Exchange 2019, 2016, 2013, 2010, 2007, 2003, and earlier versions.


Due to unknown sender, incorrect authentication, or recipient policy, an Exchange SMTP error prevents sending and receiving emails from server to client. User can try the above mentioned steps to fix this corruption error permanently.

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