Can a "mailto:" link be used within Rise?

Neat idea. Works for some things but doesn't work for this purpose, unfortunately.

I have a workaround for this and other customization to the page code. It's not as easy as using the editor but it's definitely still easy. 

1) Add your mailto: link as you would a hyperlink.

2) Once added, right-click the hyperlink and select Inspect (in Chrome -- or equivalent in other browsers)

You'll see something like this:

3) Right click the a href=" line containing your mailto link and select edit attribute. You'll now be able to remove the "http://" from the front of that link. Close your inspect window and the change should stick on your page.  Here it is after a page refresh following a client side edit. 

The environment updates to the server live based on what's in your blocks. Since the inspector modifies this directly, your changes bypass the way the editor works. This will also allow you to add complex structures such as tables. It doesn't work here because there looks to be a filter on anchor elements that automatically adds in an http:// prefix.