Printmail Form inside Colorbox
You should use the colorbox-node instead of colorbox-load First check have you already installed the Colorbox and the Colorbox Node modules.

Then, your link would be similar to the following one.

&lt;a href="/pages/demo/printmail/64?width=500&amp;height=500" class="colorbox-node"&gt;Als E-Mail versenden&lt;/a&gt;