ERROR: maximum number of tentatives has been reached

[Mike Stoltzfus]

I have one domain on my XMail server that is not able to send email.  They
can receive, but when they try to send it returns an email with the
following error:

<Failure Reason>
The maximum number of tentatives has been reached.
</Failure Reason>

Anyone know why this is happening, and how I can fix it?
-------------------------------------------
Mike Stoltzfus
Harrisonburg.Net