Sustainability of Digital Formats: Planning for Library of Congress Collections

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MBOXCL Email Format

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name MBOXCL Email Format
Description

MBOXCL 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.

Like MBOXO, MBOXCL utilizes irreversible quoting prepending one greater-than sign (“>”) before the "From " string whenever it occurs at the beginning of a line in either the header or the body of a message. Unlike MBOXO (and MBOXRD) however, MBOXCL does not scan for "From " to determine message separator points. Instead, each MBOXCL message contains a 'Content-Length:' header that denotes the length of the message body, after transformation, in bytes. This header is added to the message when it is added to the mailbox, and used to locate the start of each next message.

Production phase Used for content in initial (by message authors), middle (by archives) or final state (by message recipients/other end users).
Relationship to other formats
    Subtype of MBOX, MBOX Email Format

Local use Explanation of format description terms

LC experience or existing holdings See MBOX
LC preference See MBOX

Sustainability factors Explanation of format description terms

Disclosure See MBOX
    Documentation See MBOX
Adoption Linux email clients are more likely to use MBOXCL or MBOXCL2. 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
Pronom PUID fmt/720
See http://www.nationalarchives.gov.uk/PRONOM/fmt/720. Note that PRONOM does not specify variants of MBOX.
Wikidata Title ID Q527723
See https://www.wikidata.org/wiki/Q527723. Note that Wikidata does not specify variants of MBOX.

Notes Explanation of format description terms

General

See MBOX for compatibility issues.

History

MBOXCL is so named because messages are distinguished not by "From " lines but rather by the 'Content-Length:' (CL) header.

MBOXCL and MBOXCL2 originated from the file format used by Unix System V Release 4 mail tools


Format specifications Explanation of format description terms


Useful references

URLs


Last Updated: 03/01/2023