voicemail (n.)

late 13c., "sound made by the human mouth," from Old French voiz "voice, speech; word, saying, rumor, report" (Modern French voix), from Latin vocem (nominative vox) "voice, sound, utterance, cry, call, speech, sentence, language, word" (source also of Italian voce, Spanish voz), related to vocare "to call" (from PIE root *wekw- "to speak").

Replaced Old English stefn "voice," from Proto-Germanic *stemno, from PIE *stomen- (see stoma). Meaning "ability in a singer" is first attested c. 1600. Meaning "expression of feeling, etc." (in reference to groups of people, etc., such as Voice of America) is recorded from late 14c. Meaning "invisible spirit or force that directs or suggests," (especially in the context of insanity, as in hear voices in (one's) head, is from 1911.

"post, letters," c. 1200, "a traveling bag, sack for keeping small articles of personal property," a sense now obsolete, from Old French male "wallet, bag, bundle," from Frankish *malha or some other Germanic source, from Proto-Germanic *malho- (source also of Old High German malaha "wallet, bag," Middle Dutch male "bag"), from PIE *molko- "skin, bag."

The sense was extended to "bag full of letters" (1650s; perhaps via phrases such as a mail of letters, 1654) and "person or vehicle that carries postal matter" (1650s). From thence, to "letters and parcels" generally (1680s) and "the system of transmission by public post" (1690s).

As a newspaper name, by 1789. In 19c. England, mail was letters going abroad, while home dispatches were post. Sense of "a personal batch of letters" is from 1844, originally American English. Mail slot "narrow opening in an exterior door of a building to receive mail delivery" is by 1893, American English. OED defines it as a "letter-slit."