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I am trying to send emails from Sharepoint via SMTP server to Exhange 2007 users. Thing is, some of these users are not allowed to recieve external emails and have the "Require that all senders are authenticated" check box ticked.

Even though the Sharepoint mailbox resides locally in the Exchange as well and sending emails to users via Outlook works. Its when Sharepoint auto generates an email and sends via SMTP is when the problem occurs.

The error I get is

Diagnostic information for administrators:

Generating server: "server-name"

550 5.7.1 RESOLVER.RST.AuthRequired; authentication required

Original message headers:

Received: from "computer_name" ("ip-address") by "server-name" ("server-ip") with Microsoft SMTP Server id "smtp-server-id"; Tue, 8 Jan 2013 11:41:38 +0500 Date: Tue, 8 Jan 2013 11:46:32 +0500 To: "" Content-Transfer-Encoding: 8bit From: =?utf-8?B?RElCIFBha2lzdGFu?= "" Content-Type: text/html; charset="utf-8" Subject: *********** MIME-Version: 1.0 X-Mailer: Microsoft SharePoint Foundation 2010 Message-ID: Return-Path:

I have tried to set the following as mentioned here Exchange 2010 distribution groups don't accept internal mails through smtp:

Get-ReceiveConnector | Add-ADPermission -User 'NT Authority\Authenticated Users' -ExtendedRights ms-Exch-SMTP-Accept-Authentication

I'm not really an Exchange admin and have just recently taken over Sharepoint administration. Any help will be greatly appreciated.

Thanks! Sam

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up vote 0 down vote accepted

The problem has been solved by adding a transport rule on the Exchange Management Console whereby users for whom mail OUTSIDE the organization is blocked an exception is added to allow Sharepoint emails to them.

Steps in the following:

Also we removed the "Require that all senders are authenticated" from the mailbox and handled this check on an exchange level rather than mailbox level.

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