mail (1) Look up mail at Dictionary.com
"post, letters," c.1200, "a traveling bag," from O.Fr. male "wallet, bag," from Frank. *malha, from P.Gmc. *malho- (cf. O.H.G. malaha "wallet, bag," M.Du. male "bag"), from PIE *molko- "skin, bag." Sense extension to "letters and parcels" (18c.) is via "bag full of letter" (1650s) or "person or vehicle who carries postal matter" (1650s). The verb is 1828, Amer.Eng. In 19c. England, mail was letters going abroad, while home dispatches were post. Sense of "personal batch of letters" is from 1844, originally Amer.Eng. Related: Mailable.
mail (2) Look up mail at Dictionary.com
"metal ring armor," c.1320, from O.Fr. maille "link of mail, mesh of net," from L. macula "mesh in a net," originally "spot, blemish," on notion that the gaps in a net or mesh looked like spots.