mailbox / letterbox, post box

envelope

posting a letter

to post a letter, to mail a letter

a letter, epistle (written message or note) / (archaic) a utility paper used for various purposes, such as for jotting down notes or for wrapping items

(Kagoshima dialect) a letter, epistle (written message or note)

to put (something) in / to admit (someone) in / to tuck in (clothing)

potential of 入る (hairu)

(chiefly women's speech) first person singular pronoun: I, me

(polite) first-person singular pronoun: I, me