<div>
What if both of those parameters are set correctly but we still get this error message? &nbsp;Could it be something on the destination's side? &nbsp;Like they possibly have a bad record cached?
</div>


What if both of those parameters are set correctly but we still get this error message?  Could it be something on the destination's side?  Like they possibly have a bad record cached?

<div>
<div class="content wysiwyg-content">
We are running Exchange server 5.5 on WinNT SP6, with Outlook 2000 as the client email. &nbsp;All users sending email to a specific address outside our domain receive an error message [501 5.7.1 &lt;user.name@mycorporation.c<wbr />om&gt;... Sender IP must resolve]<br />
in a bounced email from Exchange server when sending email to this specific domain. &nbsp;<br />
<br />
We have discovered this outside domain uses reverse DNS to resolve who sends the email. &nbsp;What do we need to do resolve this to be able to send email to this specific domain?
</div>
</div>


We are running Exchange server 5.5 on WinNT SP6, with Outlook 2000 as the client email.  All users sending email to a specific address outside our domain receive an error message [501 5.7.1 <user.name@mycorporation.com>... Sender IP must resolve]
in a bounced email from Exchange server when sending email to this specific domain.  

We have discovered this outside domain uses reverse DNS to resolve who sends the email.  What do we need to do resolve this to be able to send email to this specific domain?

501 5.7.1  Sender IP must resolve

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.