hi,<br>trying to register external users and getting following message.<br><br><b>Mailbox unavailable. The server response was: 5.7.1 Client does not have permissions to send as this sender<br><br>but i am able to send mails using same smtp from outlook.<br><br><br>thanks<br></b><hr class="sig">S.Venkata Appaji© 2009 Microsoft Corporation. All rights reserved.Mon, 13 Jul 2009 12:46:40 Z170d4d38-3753-47c5-b2f4-99f06ba1891bhttp://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#170d4d38-3753-47c5-b2f4-99f06ba1891bhttp://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#170d4d38-3753-47c5-b2f4-99f06ba1891bAppajihttp://social.technet.microsoft.com/Profile/en-US/?user=Appajihi,<br>trying to register external users and getting following message.<br><br><b>Mailbox unavailable. The server response was: 5.7.1 Client does not have permissions to send as this sender<br><br>but i am able to send mails using same smtp from outlook.<br><br><br>thanks<br></b><hr class="sig">S.Venkata AppajiThu, 22 Jan 2009 19:50:39 Z2009-01-22T19:50:39Zhttp://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#320388f0-b91c-4157-ae40-9cf57504506fhttp://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#320388f0-b91c-4157-ae40-9cf57504506fWictor Wilénhttp://social.technet.microsoft.com/Profile/en-US/?user=Wictor%20Wil%u00e9n Hi, make sure that you app pool account has permissions to send through the smtp<br>/WW<hr class="sig">http://www.wictorwilen.se/Sat, 07 Feb 2009 14:05:13 Z2009-02-07T14:05:13Zhttp://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#4696e955-3045-4cbe-ad45-927dd6939916http://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#4696e955-3045-4cbe-ad45-927dd6939916D.V._rubiconict.nlhttp://social.technet.microsoft.com/Profile/en-US/?user=D.V._rubiconict.nl<p>And how exactly do you make sure that my app pool account has these permission?<br/>Thanks in advance &amp; Grtz!</p>Wed, 10 Jun 2009 08:46:28 Z2009-06-10T08:46:28Zhttp://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#4d5d6330-728a-4d86-adcc-8ccafc877886http://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#4d5d6330-728a-4d86-adcc-8ccafc877886yagyashreehttp://social.technet.microsoft.com/Profile/en-US/?user=yagyashreePlease follow this article:<br/> <br/> http://msexchangeteam.com/archive/2006/12/28/432013.aspx<br/><hr class="sig">Visit: http://yagyashree.wordpress.com MCP &amp; MCTS [WSS 3.0/MOSS]Tue, 16 Jun 2009 19:11:31 Z2009-06-16T19:11:31Zhttp://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#fc804494-87fc-4aba-a29a-51da82defed8http://social.technet.microsoft.com/Forums/en-US/sharepointcollaboration/thread/170d4d38-3753-47c5-b2f4-99f06ba1891b#fc804494-87fc-4aba-a29a-51da82defed8Manishrao Patilhttp://social.technet.microsoft.com/Profile/en-US/?user=Manishrao%20PatilHi,<br/>In my case whenever I faced this kind of issue. The main culprit was the Antiviruse that we have installed on the server. The antiviruse has property which block the mass mailing mechanism to stop even if the SMTP and other things are configure right!!<br/>Let me know your view.<hr class="sig">Manish Patil http://patilmanishrao.wordpress.com Posting is provided &quot;AS IS&quot; with no warranties, and confers no rights.Mon, 13 Jul 2009 12:46:40 Z2009-07-13T12:46:40Z