Sustainability of Digital Formats: Planning for Library of Congress Collections

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MBOXRD Email Format

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name MBOXRD Email Format
Description

MBOXRD 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.

MBOXRD was designed to solve the message corruption problems inherent in the MBOXO format. It employs "reversible From quoting" because it allows for differentiating between ">From " found in the original message from ">From " found in a transformed MBOXO file. This is important because lines that begin with ">From " act as the separator lines between email messages; if ">From " appears in any line in original text outside of the start of a new message, it will become a misplaced separator line and incorrectly mark a new message when indeed, there is no new message.

In MBOXRD files, any line of the message, in either the header or the body, that begins with zero or more '>' characters followed by the five characters 'F', 'r', 'o', 'm', and ' ', has a single greater-than sign (">") character prepended to it. When a message is read from a MBOXRD mailbox file, it is transformed back so that any line of the message, in either the header or the body, that begins with one or more '>' characters followed by the five characters 'F', 'r', 'o', 'm', and ' ', has the single leading '>' character removed from it.

Because "From " at the start of a line is more probable than ">From " in real-world messages, an MBOXRD reader will restore a greater number of messages written to a mailbox by an MBOXO tool to their original forms than an MBOXRD tool, but will not and cannot restore all messages.

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 The Mozilla family of MUAs including Thunderbird, Mozilla Suite, Netscape, Portable Thunderbird, Postbox, Spicebird, SeaMonkey as well as the open source version of Eudora use a slightly modified version of the MBOXRD variant with more complicated "From " line quoting rules. 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

MBOXRD format originated in 1995 and is named after Rahul Dhesi (hence the RD) although several people were working on the same issues during this time, Tim Goodwin being one.

qmail switched from MBOXO to MBOXRD on 1996-03-02.


Format specifications Explanation of format description terms


Useful references

URLs


Last Updated: Monday, 27-Feb-2017 09:55:24 EST