(Originally) a place where a document to be sent by electronic (facsimile) mail may be deposited for subsequent processing; (now usually, Computing) a place on a computer or network where emails to a particular user are held.
Origin
1960s.
Definition of electronic mailbox in US English:
electronic mailbox
noun
(Originally) a place where a document to be sent by electronic (facsimile) mail may be deposited for subsequent processing; (now usually, Computing) a place on a computer or network where emails to a particular user are held.