cangelly,

 
If you want to use the absolute path like (\\fileserver3\sharename\Inetpub\wwwroot\siteName\),  you should reference the use the following format:

<img src="file:\\c:\images\example.gif" width=200 height=200/>

The following format is not valid:

<img src="c:\images\example.gif" width=200 height=200/>

Or

<img src="\\fileserver3\images\example.gif" width=200 height=200/>

That's why I suggest you create a virtual directory and use the relative path:

<img src="/mockup/example.gif" width=200 height=200/>