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HI Sir,<br />
<br />
i'm also getting the same error &nbsp; 503 valid RCPT command must precede DATA i'm using &nbsp;outlook 2007 and &nbsp;connection type is pop i tried all the website also nothing is working i even tried my server requried authentification still does not work my mail server is in linux and few staff getting this error rest all fine <br />
<br />
please help me sir..<br />
<br />
thanks in advance 
</div>


HI Sir,

i'm also getting the same error   503 valid RCPT command must precede DATA i'm using  outlook 2007 and  connection type is pop i tried all the website also nothing is working i even tried my server requried authentification still does not work my mail server is in linux and few staff getting this error rest all fine

please help me sir..

thanks in advance

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<div class="content wysiwyg-content">
Here's an email that came back:<br />
<br />
     user@mail.ru on 10/28/2008 2:27 PM &nbsp;            There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator. &nbsp;            &lt;domain.com #5.5.0 smtp;503 valid RCPT command must precede DATA&gt; &nbsp;<br />
<br />
<br />
after some research it seems that acceptable workaround for this to enable&quot;my server requires authentication&quot; for a pop3 box. however my users are using a exchange server without pop3 connector. i see the following options under Outlook 2007 exchange options&gt; security &gt;&nbsp;network security: negotiate authentication, kerberos, ntlm.<br />
<br />
Whats the proper authentication method to fix the issue stated above? sorry this is a live server and I dont want to play test and trial game on this one. 
</div>
</div>


Here's an email that came back:

     user@mail.ru on 10/28/2008 2:27 PM              There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.              <domain.com #5.5.0 smtp;503 valid RCPT command must precede DATA>  


after some research it seems that acceptable workaround for this to enable"my server requires authentication" for a pop3 box. however my users are using a exchange server without pop3 connector. i see the following options under Outlook 2007 exchange options> security > network security: negotiate authentication, kerberos, ntlm.

Whats the proper authentication method to fix the issue stated above? sorry this is a live server and I dont want to play test and trial game on this one. 

503 valid RCPT command must precede DATA on Exchange 2003 using Outlook 2007

Networking is the process of connecting computing devices, peripherals and terminals together through a system that uses wiring, cabling or radio waves that enable their users to communicate, share information and interact over distances. Often associated are issues regarding operating systems, hardware and equipment, cloud and virtual networking, protocols, architecture, storage and management.

Networking

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

Exchange

Microsoft Outlook is a personal information manager from Microsoft, available as a part of the Microsoft Office suite. Although often used mainly as an email application, it also includes a calendar, task manager, contact manager, note-taker, journal, and web browser.