What is EMLX file Format?

EMLX file format is used for a text file that is implemented and developed by Apple. It is related to Apple Mail and is used in Apple Mac OS X. Normally, it is stored as a plain text file and can be opened using any text editor.

Brief History

Mac OS X operating system adopted the existing email program, NeXTMail, created by NeXT as a part of NeXTSTEP operating system. After acquiring NeXT, Apple uplifts its features and became the Apple Mail email application to be used as a default email client. Emails exported from Apple Mail are saved as EMLX files.

File Format Specifications

EMLX is a single email message file and can be opened easily with any Text editor like Notepad. EMLX file structure consists of three parts –

A byte count for the email message – length of the message itself, written in ASCII in decimal.
The message itself
Message metadata

This can be better known with the help of the sample email extracted from Apple Mail as EMLX and opening it in a text editor.

622       
X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on ******.*********.***
X-Spam-Level:
X-Spam-Status: No, score#-3.2 required#4.2 tests#BAYES_00,RP_MATCHES_RCVD,
        SPF_PASS,TVD_SPACE_RATIO autolearn#ham version#3.3.2
Received: from [127.0.0.1] (******.*********.*** [***.**.**.**])
        by ******.*********.*** (8.14.5/8.14.5) with ESMTP id r2TN8m4U099571
        for <****@*********.***>; Fri, 29 Mar 2013 19:08:48 -0400 (EDT)
        (envelope-from ****@*********.***)
Subject: very simple
From:  <****@*********.***>
Content-Type: text/plain; charset#us-ascii
Message-Id: <4E83618E-BB56-404F-8595-87352648ADC7@*********.***>
Date: 14 Feb 2013 15:33:54 +0530
To: Reciever <****@*********.***>
Content-Transfer-Encoding: 7bit
Mime-Version: 1.0 (Apple Message framework v1283)
X-Mailer: Apple Mail (2.1283)

message Foot
--
Sender
http://www.la-grange.net/karl/

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version#"1.0">
<dict>
        <key>date-sent</key>
        <real>1364598546</real>
        <key>flags</key>
        <integer>8590195713</integer>
        <key>original-mailbox</key>
        <string>imap://********@127.0.0.1:11143/mail/2013/03</string>
        <key>remote-id</key>
        <string>41147</string>
        <key>subject</key>
        <string>very simple</string>
</dict>
</plist>

In this example, 622 indicates the total length of the message. The message meta data is enclosed in tags and the tags are described as follows;

Field	Description	Value
0	read	1 « 0
1	deleted	1 « 1
2	answered	1 « 2
3	encrypted	1 « 3
4	flagged	1 « 4
5	recent	1 « 5
6	draft	1 « 6
7	initial (no longer used)	1 « 7
8	forwarded	1 « 8
9	redirected	1 « 9
10-15	attachment count	3F « 10 (6 bits)
16-22	priority level	7F « 16 (7 bits)
23	signed	1 « 23
24	is junk	1 « 24
25	is not junk	1 « 25
26-28	font size delta	7 « 26 (3 bits)
29	junk mail level recorded	1 « 29
30	highlight text in toc	1 « 30
31	(unused)

What is EMLX file Format?

Available Online Conversion