Another way you could do it:
use the 'Link button' widget, which is part of the core Mendix widget set.
Nice thing about this widget is that you can use a static link but also a dynamic link based on an attribute of an Entity
Hi Enzo, you might try my DivButtonHelper widget, which makes any Mendix container clickable. I just tested it, and it works well for mailto URLs as well.
Direct download: here
Repository: here
I've seen a lot of use cases recently for this widget, so I've just submitted this to the app store for approval.
Hi Enzo,
As an alternative to Eric's answer, you can base64 encode your image and use that value in the html snippet. Instead of uploading your image to an external server.