<div>
Do you have a web-shield set up? If so you might want to take a look into it.
</div>


Do you have a web-shield set up? If so you might want to take a look into it.

<div>
Is the mailbox actually existing??<br />
<br />
It could be that the user of the mailbox, first needs to login to actually enable the mailbox
</div>


Is the mailbox actually existing??

It could be that the user of the mailbox, first needs to login to actually enable the mailbox

<div>
the mailbox does exist.....the user is able to receive emails from co-workers. &nbsp;do not have a web shield set up
</div>


the mailbox does exist.....the user is able to receive emails from co-workers.  do not have a web shield set up

<div>
is it only from a particular address...how about send from ANOTHER email address?
</div>


is it only from a particular address...how about send from ANOTHER email address?

<div>
i tried sending from 3 different email addresses and get the same error.....
</div>


i tried sending from 3 different email addresses and get the same error.....

<div>
Have you looked at your smpt connectors?
</div>


<div>
yes i have it looks fine.....the strange thing is everyone gets external emails except for this one user.....
</div>


yes i have it looks fine.....the strange thing is everyone gets external emails except for this one user.....

<div>
<div class="content wysiwyg-content">
When I send an email from an outside source to one of my companies email address, I get an error message stating:<br />
<br />
5.1.0 - Unknown address error 550-'5.7.1 Requested action not taken: mailbox not available'<br />
<br />
help......
</div>
</div>


When I send an email from an outside source to one of my companies email address, I get an error message stating:

5.1.0 - Unknown address error 550-'5.7.1 Requested action not taken: mailbox not available'

help......

5.1.0 - Unknown address error 550-'5.7.1 Requested action not taken: mailbox not available'

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.