c.1300, "communication transmitted via a messenger," from Old French message "message, news, tidings, embassy" (11c.), from Medieval Latin missaticum, from Latin missus "a sending away, sending, despatching; a throwing, hurling," noun use of past participle of mittere "to send" (see mission). The Latin word is glossed in Old English by ærende. Specific religious sense of "divinely inspired communication via a prophet" (1540s) led to transferred sense of "the broad meaning (of something)," first attested 1828. To get the message "understand" is from 1960.
To send a message on the Internet •The sense ''to send a message'' is found by 1583: '' I need to do it,'' Baker messaged a man with whom he had been discussing rape, torture, and murder (1990s+ Computer)