Using different icons for social sharing menus

Hi,

In the site I’m currently working on we have a sharing menu in the header, and I’d like to use the mail envelope for the icon leading to our “contact us” page with an email form. It’s not a supported link by Genericon, so it defaults to the star icon. Is there a way to change the icon without going into the code and doing it manually? Or is that the only option, and how do I do it if so?