Resolve 5.7.1 Client Was Not Authenticated in Exchange 2010

MS Exchange Server functions as an email client and calendaring tool that has been developed by Microsoft and runs on Windows Server family. Usually in most of Exchange Server 2010 platforms, there is a need to control the settings for allowing certain hosts or applications to use email services through Exchange Server. Sometimes, user may face issue when they are not able to receive email due to default settings present in SMTP Receive Connector of Exchange Server 2010. The Error is commonly known as “530 5.7.1 Client was not authenticated”. The blog will be describing the error in depth and the possible solutions to resolve the same error faced in Exchange Server 2010.

About the Error 530 5.7.1 Client was not authenticated

In an Exchange organization, Hub Transport Server is used to control any SMTP communication. The transport service depends on Receive Connector for SMTP connections. However, the default settings of this connector are secured to restrict any anonymous connections (Apart from connections made by non-Exchange System). An error will be encountered while user is trying to start unauthenticated SMTP communications. Due to this error, user may have issue in receiving mails. The sending host will receive following error message- “530 5.7.1 client was not authenticated” on SMTP handshake from the mail server of Exchange 2010.

Telnet session to check the Error

Before starting the steps to resolve the error, let us understand the response of the mail server. We will open telnet session to the mail server using SMTP commands to view the error message by following the steps below:

• Open DOS/PowerShell & type ‘servermanagercmd –install telnet-client’

• After successful installation, we will telnet into port 25 of the mail server with the commands: telnet exchange.<servername>.com 25

• 220 exchange.<servername>.com will be displayed on the command prompt screen

• Type ‘Hello’ & the server will respond ‘250 exchange.<servername>.com Hello’

• we will relay to it using ‘mail from:<servername>@me.com’

• we get the error displayed ‘530 5.7.1 client was not authenticated’

 Approach to troubleshoot the Error in Exchange 2010

In order to fix the error 5.7.1 client was not authenticated exchange 2010, steps to be followed to make changes at the Receive Connector (part of Hub Transport) for Exchange are:

• Open Exchange Management Console or Exchange System Manager

• Select Hub Transport found under Server Configuration Tab

• Look for default Receive Connector on the screen

• Select the Receive Connector and Right-click on it

• Click on Properties of the Connector and go to Permission Groups

• Here, we can specify the type of users that are allowed to connect to this Receive Connector.

• Check the box of Anonymous Users and other Exchange users, servers, legacy Exchange Servers

• Checking the Anonymous Users will allow another mail server to communicate with your mail server.

• Click on Apply to save the changes made in the settings of Receive Connector
• Stop or disable and restart the Connector to make the changes work

Conclusion: In the blog, we have studied about the above error encountered by the users of Exchange Server 2010 while trying to initiate unauthorized SMTP connections. The error restrict user while receiving emails from connections made by non-Exchange Systems. In order to resolve the issue, we will change the settings of the default Receive Connector that will allow anonymous users and save the modifications. If Exchange admin is unable to set the settings to the default which in turn unable to resolve 530 5.7.1 Client was not authenticated by using above method then it means there is some problem in Exchange database which cannot be resolved manually. This issue can be resolved if the database get repaired and then mount back to the Exchange Server 2010 by using a third party tool such as Exchange Recovery Software which supports all versions of Exchange Server.