Allow Exchange 2010 to relay to external email address

Posted on 2012-09-18
Last Modified: 2012-10-05
I have configured a new Receive Connector in our Exchange 2010 (SBS2011) to allow a Voicemail application on one of our Windows 2008 R2 server to send emails (voicemails) to the internal users. It is configured with no authentication (anonymous). All works fine.

But I would also need to be able to send voicemail emails to external Internet email addresses. When I test it from Telnet, I get a relaying error from Exchange (550 5.7.1 Unable to relay) right after entering the "rcpt" command. The same Telnet test to an internal user works fine. Do I need to change something in the Receive Connector to allow relaying to the Internet, or something else ?

Sequence of telnet commands I try to use when testing to external email address (I get the error 5.7.1 Unable to relay after the rcpt to: command):

(start of telnet session)
set localecho
open 25
Subject: Test message from Voicemail server

This is a test message from the Voice Mail server.
(end of telnet session)

Question by:ndidomenico
    LVL 35

    Expert Comment

    by:Cris Hanna
    do these "external recipients" also have Exchange mailboxes??
    LVL 23

    Accepted Solution

    Your problem seems similar with this article:
    Check the permissions on that Receive Connector.
    LVL 18

    Assisted Solution

    1. Create a Receive Connector
    2. Grant Relay permission to the Receive Connector via cmdlet as below:

    Get-ReceiveConnector "Anonymous Relay" | Add-ADPermission -User "NT AUTHORITY\ANONYMOUS LOGON" -ExtendedRights "Ms-Exch-SMTP-Accept-Any-Recipient"

    Open in new window
    LVL 15

    Assisted Solution

    You need to create a receive connector configured as "externally secured".. this will allow your server to send anonymous e-mail to the Internet. Please be sure that you bind that connector only to the specific server (or other servers with the same requirements). Now the important part. How to do it:

    hope it helps

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