Sustainability of Digital Formats: Planning for Library of Congress Collections

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MBOXO Email Format

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name MBOXO Email Format
Description

MBOXO is one of the MBOX family of related file formats used for holding collections of electronic mail messages. See MBOX for a description of the syntax.

Since all MBOX messages are concatenated into one text file, MBOXO (and MBOXRD) formatted messages locate the message start by scanning for “From ” lines. If a "From " string occurs at the beginning of a line in either the header or the body of a message, the e-mail message must be modified before the message is stored in an MBOX mailbox file or the line will be taken as the start of the new message. MBOXO files prepends one greater-than sign (“>”) to any line of the message, in either the header or the body, that begins with the five characters 'F', 'r', 'o', 'm', and ' ' (“>From ”).

According to Jonathan de Boyne Pollard, messages appended to an MBOXO mailbox are irrevocably corrupted by prepending the “>” before the word "From" because it is impossible to determine if the “>” was already present as a character in the original message. If a line already contained ">From " at the beginning (such as in a quotation), it is unchanged when written.

Relationship to other formats
    Subtype of MBOX, MBOX Email Format

Local use Explanation of format description terms

LC experience or existing holdings  
LC preference  

Sustainability factors Explanation of format description terms

Disclosure See MBOX
    Documentation See MBOX

Adoption

Eudora uses an mboxo variation where a sender's e-mail address is replaced by the constant string "???@???"

See also MBOX
    Licensing and patents See MBOX
Transparency See MBOX
Self-documentation See MBOX
External dependencies See MBOX
Technical protection considerations See MBOX

Quality and functionality factors Explanation of format description terms


File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension See related format.  See MBOX
Internet Media Type See related format.  See MBOX
Magic numbers See related format.  See MBOX

Notes Explanation of format description terms

General

See MBOX for compatibility issues.

History  

Format specifications Explanation of format description terms


Useful references

URLs


Last Updated: 02/27/2017