Systems and methods for delivering media files in communication sessions are disclosed. User interfaces are displayed on first and second client devices. A media file is selected at the first client device and a representation of the media file is transmitted to the second client device. The representation is selectable within a sent message region of the user interface on the second client device. In response to selecting the representation of the media file, an embedded viewer is launched within the sent message region of the user interface of the second client device that includes embedded selectable controls which, when activated, control viewing or playback of the media file within the user interface.