SMTP stands for Simple Mail Transfer Protocol that works to send emails between the server and its email clients. However, sometimes, you will face some issue like 550 5.7.1 while trying to send emails. Let’s find out what is Exchange SMTP error 550 5.7.1.

What is Error SMTP error 550 5.7.1?

The SMTP error 550 5.7.1 occurs in In Exchange 2016, 2013, 2010 or 2007 versions while users trying to send emails. If Exchange finds that any unauthorized user is accessing the Exchange Server, then it will display SMTP error 550 5.7.1 with the error message “Unable to relay.”

This error can happen to any user and can block emails from being sent. This error consists of three-digit codes, and each digit has a meaning.

What are the causes of SMTP error 550 5.7.1?

There are some factors which are responsible for this error like:

  • There is an unknown sender, or the Outgoing Mail Server does not recognize the sender.
  • Sender domain fails to be authenticated
  • The recipient policy of the receiver domain blocks emails from the sender domain.

How to fix 550 5.7.1 error unable to relay in Exchange Server

  1. Launch Exchange Server Manager and move to Administrative Groups.
  2. Select Administrative Group Name then choose Server>Server Name.
  3. Now click on Protocols and Select SMTP.
  4. Right-click on Default SMTP Virtual Server and Select Properties
  5. In Access tab, click on Relay>only the list below
  6. Now check the checkbox “Allow all systems to successfully authenticate to relay regardless of the list above” and close.

Now you can send messages as normal.

What to do if you are not able to send messages because of EDB corruption?

Kernel for Exchange Server Recovery helps you in repairing your corrupted EDB files.

Sometimes users will find that maiboxes are inaccessible due to damaged EDB files. So, repair your EDB files with this fully automated tool. With this comprehensive Exchange Server Recovery tool, you can migrate your repaired EDB files to Live Exchange or Office 365. It has options to migrate mailboxes from Live Exchange to Office 365 and vice versa. The software works with all versions of MS Exchange Server and Windows OS, and all plans of Office 365.

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