How to resolve "530 5.7.1 client was not authenticated" error In Exchange 2007, 2010, and 2012

When sending an email from outside your network to your domain using ES, you may see the following error on the ES device either on auditing page or under MTA status page where the emails are stuck in the MTA and not getting delivered to your exchange server.

If you run a telnet test from the ES device using the CLI to your exchange you may see the following error:

• SNWLCLI:> Telnet 192.168.1.3 25.
• mail2.smtp25.org Microsoft ESMTP mail service.
• helo ( hit enter).
• 220 mail2.smtp25.org Microsoft ESMTP mAIL service.
• 250 mail2.smtp25.org Hello [10.10.10.10].
• mail from:Test123@Gmail.com ( Use yours) hit enter.
• 530 5.7.1 Client was not authenticated.

This can be fixed by changing a setting on Exchange server.

1. Login to Exchange server.
2. Navigate to Exchange Organization|Server configuration.
3. Click Hub transport and select the server default receive connector.
4. Right click and select properties.
5. Click on last tab permission Groups.
6. Place check mark into Anonymous users.
7. Click Apply and OK.