An email mailbox (also email box, e-mailbox) is the equivalent of a letter box for electronic mail, it is where electronic mail messages are delivered.

Definitions

A mailbox can be identified by an email address. However, not all email addresses correspond to a physical storage location. The term pseudo-mailbox is sometimes used to refer to an address that does not correspond to a definitive end user. Email forwarding may be applied to reach end recipients from such addresses. Electronic mailing lists and email aliases are typical examples.

RFC 5321, defines an email address as a character string that identifies a user to whom mail will be sent or a location into which mail will be deposited. The term mailbox refers to that depository. In that sense the terms mailbox and address can be used interchangeably.

RFC 5322 features a slightly different usage. It mentions: A mailbox receives mail. It is a 'conceptual entity' that does not necessarily pertain to file storage. It further exemplifies that some sites may choose to print mail on a printer and deliver the output to the addressee's desk, much like a traditional fax transmission.