Not sure if this is related to flarum core, or FoF pretty mail, but new user signup emails (and perhaps other templates) that are not configurable and rely on the default template, use the users username, rather than display name. For forums where the username is not user friendly the display name should be used in really all places besides user sign in.
Is it possible for pretty mail to support more templates, such as user signup so we can ensure the correct fields are used?
