mbox
also: mailbox format, mbox format
A mailbox file format that stores multiple email messages in a single plain-text file, with each message separated by a line starting with 'From ' (with a space).
mbox (mailbox) is one of the oldest and most widely supported email storage formats on Unix and Linux systems. All messages are concatenated into a single file, making it simple but potentially slow for large mailboxes.
Each message is separated by a line beginning with From (literally the word "From" followed by a space), which contains the sender's address and delivery timestamp. This format is human-readable and can be edited with any text editor, though this is not recommended for active mailboxes.
Example structure:
From sender@example.com Mon Jan 15 10:30:00 2024
From: sender@example.com
To: user@localhost
Subject: Hello
Message body here
From recipient@example.com Mon Jan 15 10:45:00 2024
From: recipient@example.com
Subject: Reply
Reply bodyMany mail clients (Thunderbird, Mutt, Alpine) and tools (Dovecot, Postfix) still support mbox, though newer formats like Maildir are often preferred for better concurrency and reliability.