1. A system that enables an individual sender to communicate messages to a receiver by exhibiting a sequence of at least a first and second facial expression, the system comprising: at least one stand-off digital image sensing device configured to capture digital images of facial expressions of the sender; a digital control unit having at least one computer processor, memory, non-volatile data storage, and communication interface, such that the at least one computer processor is in operable communication with the memory, data storage, and image sensing device; a receiver interface in communication with the digital control unit via the communication interface; the data storage comprising a background model, a first expression model, and a second expression model, the background model adapted to characterize a plurality of pixels from at least a portion of an image outside the region of interest of the sender's face, the first expression model adapted to characterize a plurality of pixels within an image of the region of interest of the sender's face when the sender is exhibiting an enrolled first facial expression, the second expression model adapted to characterize a plurality of pixels within an image of the region of interest of the sender's face when the sender is exhibiting an enrolled second facial expression, wherein the first and second expression models characterize the plurality of pixels as a function of location (m, n), orientation (φ, θ, ψ), and size(s) of the region of interest within a captured image to accommodate variation in relative stand-off distance and orientation of the at least one digital imaging device to the sender, the data storage further comprising at least one enrolled message associated with a sequence of a first and second enrolled expressions of the sender; the digital control unit comprising computer programming code having an expression identifier and a sequence decoder, the at least one computer processor configured by the computer programming code, the computer programming code adapted to inter-relate with the digital imaging device, the background model, and the first and second expression models to locate the facial region of interest of the sender and to capture first and second images of the region of interest of the sender, the computer programming code further adapted to perform the steps of: (a) applying the expression identifier to the first and second captured images with the first and second expression models to classify each of the first and second captured images as exhibiting (i) the enrolled first facial expression, (ii) the enrolled second facial expression, or (iii) no enrolled facial expression; (b) decoding the classified first and second captured images with the sequence decoder based on a matching score to determine if the classified first and second images satisfy a predetermined likelihood of communicating the at least one enrolled message; and (c) communicating the at least one enrolled message to a receiver via the receiver interface.