An electronic communication system provides text or voice messages to remote receiving devices, such as cell phones or PDA's. The remote receiving devices are equipped with velocity sensors, or position sensors from which velocity may be inferred. The remote receiving devices periodically report a velocity or current position to an alert signal control node of the communication system. The alert signal control node determines a most recent-determinable velocity for each receiving device before transmitting a message alert signal. If the velocity exceeds a predetermined threshold, the alert signal may be delayed until the velocity drops below the threshold. The system may be operated as a safety measure to prevent reception of distracting alert signals while driving, thereby silencing messaging devices at appropriate times.