mail vs missive

mail and missive both are nouns.

Word	Noun	Adjective	Verb	Adverb
mail	Yes	No	Yes	No
missive	Yes	No	No	No

mail (noun)	missive (noun)
(Middle Ages) flexible armor made of interlinked metal rings	a written message addressed to a person or organization
a conveyance that transports the letters and packages that are conveyed by the postal system
the system whereby messages are transmitted via the post office
the bags of letters and packages that are transported by the postal service
any particular collection of letters or packages that is delivered

mail (verb)	missive (verb)
cause to be directed or transmitted to another place
send via the postal service