Editing Mbox (section)

{{Short description|Family of email-related file formats}}
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'''Mbox''' is a generic term for a family of related [[file format]]s used for holding collections of [[email]] messages. It was first implemented in [[Research Unix|Fifth Edition Unix]].

All messages in an mbox mailbox are [[Concatenation|concatenated]] and stored as [[plain text]] in a single file. Each message starts with the four characters "From" followed by a space (the so-called "From_ line") and the sender's email address. RFC 4155 defines that a [[UTC]] timestamp follows after another separating space character.<ref name="RFC4155">{{cite web |editor-last=Hall |editor-first=E. |title=Request for Comments: 4155 – The application/mbox Media Type |url=https://datatracker.ietf.org/doc/html/rfc4155 |date=September 2005 |website=[[Internet Engineering Task Force]] |access-date=17 May 2021 |archive-date=17 May 2021 |archive-url=https://web.archive.org/web/20210517200708/https://datatracker.ietf.org/doc/html/rfc4155 |url-status=live }}</ref>

A format similar to mbox is the [[MH Message Handling System]]. Other systems, such as [[Microsoft Exchange Server]] and the [[Cyrus (imapd)|Cyrus IMAP]] server, store mailboxes in centralized databases managed by the mail system and not directly accessible by individual users. The [[maildir]] mailbox format is often cited as an alternative to the '''mbox''' format for networked email storage systems.