Link to Custom URIs?

Link to Custom URIs?

Is it possible to link URIs in SDP replies other than http(s): or mailto:? For example, is there a way I can link a user to a specific page in SCCM's Software Center using its URI? Like this? Download from Software Center.

I've tried:
  1. Using the Insert Link function. This results in it prepending http: before the actual URI.

  2. Editing HTML within the editor. This results in a broken link.

We have begun using these URIs within our company for communications with end users. However, we can't seem to use these in SDP, which severely limits how we can use these, as we would primarily send these links in SDP. Maybe there's an advanced configuration that would need to be completed on the server itself? Any thoughts or suggestions appreciated.