"BLOCKED::" is not blocked

Hi,

I have an application that generates an email message that Outlook displays
in HTML.
Imbedded in the html are some references to an application. When a user
gets the message and clicks the link, the application opens and displays the
intended information.
A sample of the HTML is
<a href="myappl:10000006">View Document ID:10000006</a> <br />

The "problem" is that when a user hovers their mouse over the link, the
tootltip(?) that displays has the contents "BLOCKED::myappl:10000006".
This is mis-leading users to think that they can't open the application,
when in fact they can.

What is causing the "BLOCKED::" to be prepended to the href?
How can I prevent "BLOCKED::" from being displayed?

Thanks,

Bob