A graphical user interface on a display device of a computer enables communications using a computer service. The graphical user interface includes a list of potential message recipients selected by a user as significant to the user. The graphical user interface also includes a mobile device identifier associated with one or more of the listed potential message recipients and a user account identifier associated with one or more of the listed potential message recipients. At least one of the listed potential recipients includes a mobile device identifier as the only available conduit for data delivery to the potential message recipient using the computer service.