<div>
It appears as though he or his ISP is blocking messages from your IP address (216.135.208.206) from being delivered. &nbsp;It is possible that the IP is on a blacklist.
</div>


It appears as though he or his ISP is blocking messages from your IP address (216.135.208.206) from being delivered.  It is possible that the IP is on a blacklist.

<div>
Sorry, left the reply window open so my first reply is not helpful. &nbsp;Anyway, I would suggest you contact &quot;abuse@att.net&quot; to inquire why they are blocking your server.
</div>


Sorry, left the reply window open so my first reply is not helpful.  Anyway, I would suggest you contact "abuse@att.net" to inquire why they are blocking your server.

<div>
<div class="content wysiwyg-content">
 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;There was a SMTP communication problem with the recipient's email server. &nbsp;Please contact your system administrator.<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &lt;mail.thhill.com #5.5.0 smtp;550-216.135.208.206 blocked by ldap:ou=rblmx,dc=worldnet,<wbr />dc=att,dc=<wbr />net&gt;<br />
<br />
<br />
is this my side or his
</div>
</div>


            There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
            <mail.thhill.com #5.5.0 smtp;550-216.135.208.206 blocked by ldap:ou=rblmx,dc=worldnet,dc=att,dc=net>


is this my side or his

#5.5.0 smtp;550

Interactions between email servers and clients are governed by email protocols. The three most common email protocols are POP, IMAP and MAPI. Most email software operates under one of these (and many products support more than one).  The correct protocol must be selected, and correctly configured, if you want your email account to work.

Email Protocols

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.