530 5.7.1 Client was not authenticated - Exchange 2013 to external domains

Hi all,

I have an Exchange server 2013 on windows 2012 R2 and do all the configuration for sending and receiving the mail according to the document provided by Microsoft.

But whenever I am trying to send mails from external domains to my exchange server domain I got the following error:

530 5.7.1 Client was not authenticated

Same thing I am getting If I am sending mail through outlook from my Exchange domains to external domain.

But if I am selecting the<label for="ResultPanePlaceHolder_ReceiveConnector_Security_contentContainer_chkPermissionGroupAnonymousUsers" id="ResultPanePlaceHolder_ReceiveConnector_Security_contentContainer_chkPermissionGroupAnonymousUsers_label">Anonymous users in the security option of Default Frontend XXXX, I am able to send the mails through outlook.</label>

<label for="ResultPanePlaceHolder_ReceiveConnector_Security_contentContainer_chkPermissionGroupAnonymousUsers" id="ResultPanePlaceHolder_ReceiveConnector_Security_contentContainer_chkPermissionGroupAnonymousUsers_label">But I don't want to use this option as it will enable to send the mails without validating the Exchange server user name and password.</label>

SO can anyone please suggest some solutions to resolve this as using Anonymous users fro sending and receiving mails is not secure.

Regards

Pankaj Raman.

<label for="ResultPanePlaceHolder_ReceiveConnector_Security_contentContainer_chkPermissionGroupAnonymousUsers" id="ResultPanePlaceHolder_ReceiveConnector_Security_contentContainer_chkPermissionGroupAnonymousUsers_label">
</label>