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Did you check the user's Outlook Block List?<br />
<br />
1.On the Tools menu, click Options.<br />
2.On the Preferences tab, under E-mail, click Junk E-mail.<br />
3.Click the Blocked Senders tab.<br />
<br />
Also, this could be your culprit:<br />
<br />
The symptom can occur if the e-mail is blocked by Outlook block list or Sender Filter agent in Edge Transport Server. For more information about Sender Filter agent, please refer to the following article:<br />
<br />
&nbsp;<br />
<br />
<a href="http://technet.microsoft.com/en-us/library/bb124354.aspx" rel="ugc">http://technet.microsoft.com/en-us/library/bb124354.aspx</a>&nbsp;<br />
<br />
&nbsp;<br />
<br />
At this stage, please check whether Anti-spam function is installed on Hub Transport Server. If so, please locate Sender Filter agent and clear the email sender. <br />

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Did you check the user's Outlook Block List?

1.On the Tools menu, click Options.
2.On the Preferences tab, under E-mail, click Junk E-mail.
3.Click the Blocked Senders tab.

Also, this could be your culprit:

The symptom can occur if the e-mail is blocked by Outlook block list or Sender Filter agent in Edge Transport Server. For more information about Sender Filter agent, please refer to the following article:

 

http://technet.microsoft.com/en-us/library/bb124354.aspx [http://technet.microsoft.com/en-us/library/bb124354.aspx] 

 

At this stage, please check whether Anti-spam function is installed on Hub Transport Server. If so, please locate Sender Filter agent and clear the email sender.


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Sorry, I did check the ETS ad Outlook/OWA. &nbsp;Nothing listed to block it. &nbsp;Thanks for the advice though.
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Sorry, I did check the ETS ad Outlook/OWA.  Nothing listed to block it.  Thanks for the advice though.

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Exchange is blocking messages to one of my users from one of his contacts. &nbsp;This contact is able to send messages to everyone else in the domain, and this user is able to receive messages form everyone but this contact. &nbsp;There are no rules in place blocking that contact, we have even white-listed the senders entire server farm, but continue to get calls about &quot;(our exchange server)said: 554 5.1.0 Sender denied (in reply to end of DATA command)&quot;.
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Exchange is blocking messages to one of my users from one of his contacts.  This contact is able to send messages to everyone else in the domain, and this user is able to receive messages form everyone but this contact.  There are no rules in place blocking that contact, we have even white-listed the senders entire server farm, but continue to get calls about "(our exchange server)said: 554 5.1.0 Sender denied (in reply to end of DATA command)".

Blocked sender

Various techniques are used to prevent email spam (unsolicited bulk email). No technique is a complete solution to the spam problem, and each has trade-offs between incorrectly rejecting legitimate email (false positives) vs. not rejecting all spam (false negatives) - and the associated costs in time and effort. Anti-spam techniques can be broken into four broad categories: those that require actions by individuals, those that can be automated by email administrators, those that can be automated by email senders and those employed by researchers and law enforcement officials.

AntiSpam

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.