Transport Neutral Encapsulation Format
Encyclopedia
Transport Neutral Encapsulation Format or TNEF is, despite the name, a proprietary E-mail
attachment format used by Microsoft Outlook
and Microsoft Exchange Server
. An attached file
with TNEF encoding is most often named winmail.dat or win.dat, and has a MIME type of Application/MS-TNEF.
The official (IANA
) media type, however is application/vnd.ms-tnef
.
) documents or Outlook-specific features such as forms, voting buttons, and meeting requests. Other TNEF files may contain files which have been attached to an e-mail message.
Within the Outlook e-mail client
TNEF encoding cannot be explicitly enabled or disabled (except via a registry setting). Selecting RTF
as the format for sending an e-mail implicitly enables TNEF encoding, using it in preference to the more common and widely compatible MIME
standard. When sending plain text
or HTML
format messages, some versions of Outlook (apparently including Outlook 2000) prefer MIME, but may still use TNEF under some circumstances (for example, if an Outlook feature requires it).
TNEF attachments can contain security-sensitive information such as user login name and file paths, from which access controls could possibly be inferred.
) compliant because these messages have the following characteristics:
Internal communications between Exchange Servers (2000 and later) over SMTP encode the message in S/TNEF (Summary TNEF) format. The conversion between the format needed by the end client on the internet is performed on the last Hub Transport server before final delivery, and when the Hub Transport role of an Exchange Server is about to deliver the message to a mailbox role server, the message is converted to MAPI format for storage.
S/TNEF differs from TNEF in that it is 8-bit (not 7-bit for TNEF) and does not contain a plain-text portion.
E-mail
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
attachment format used by Microsoft Outlook
Microsoft Outlook
Microsoft Outlook is a personal information manager from Microsoft, available both as a separate application as well as a part of the Microsoft Office suite...
and Microsoft Exchange Server
Microsoft Exchange Server
Microsoft Exchange Server is the server side of a client–server, collaborative application product developed by Microsoft. It is part of the Microsoft Servers line of server products and is used by enterprises using Microsoft infrastructure products...
. An attached file
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
with TNEF encoding is most often named winmail.dat or win.dat, and has a MIME type of Application/MS-TNEF.
The official (IANA
Internet Assigned Numbers Authority
The Internet Assigned Numbers Authority is the entity that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System , media types, and other Internet Protocol-related symbols and numbers...
) media type, however is application/vnd.ms-tnef
.
Overview
Some TNEF files contain information used by only Outlook to generate a richly formatted view of the message, such as embedded (OLEObject Linking and Embedding
Object Linking and Embedding is a technology developed by Microsoft that allows embedding and linking to documents and other objects. For developers, it brought OLE Control eXtension , a way to develop and use custom user interface elements...
) documents or Outlook-specific features such as forms, voting buttons, and meeting requests. Other TNEF files may contain files which have been attached to an e-mail message.
Within the Outlook e-mail client
E-mail client
An email client, email reader, or more formally mail user agent , is a computer program used to manage a user's email.The term can refer to any system capable of accessing the user's email mailbox, regardless of it being a mail user agent, a relaying server, or a human typing on a terminal...
TNEF encoding cannot be explicitly enabled or disabled (except via a registry setting). Selecting RTF
Rich Text Format
The Rich Text Format is a proprietary document file format with published specification developed by Microsoft Corporation since 1987 for Microsoft products and for cross-platform document interchange....
as the format for sending an e-mail implicitly enables TNEF encoding, using it in preference to the more common and widely compatible MIME
MIME
Multipurpose Internet Mail Extensions is an Internet standard that extends the format of email to support:* Text in character sets other than ASCII* Non-text attachments* Message bodies with multiple parts...
standard. When sending plain text
Plain text
In computing, plain text is the contents of an ordinary sequential file readable as textual material without much processing, usually opposed to formatted text....
or HTML
HTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
format messages, some versions of Outlook (apparently including Outlook 2000) prefer MIME, but may still use TNEF under some circumstances (for example, if an Outlook feature requires it).
TNEF attachments can contain security-sensitive information such as user login name and file paths, from which access controls could possibly be inferred.
Exchange Server
Native-mode Microsoft Exchange 2000 organizations will in some circumstances send entire messages as TNEF encoded raw binary independent of what is advertised by the receiving SMTP server. As documented in Microsoft KBA #323483, this technique is not RFC (Request for CommentsRequest for Comments
In computer network engineering, a Request for Comments is a memorandum published by the Internet Engineering Task Force describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.Through the Internet Society, engineers and...
) compliant because these messages have the following characteristics:
- They may include non-ASCII characters outside the 0–127 US-ASCII range.
- The lines in these messages are often too long for transport via SMTP.
- They do not follow the CRLF.CRLF line termination semantics as specified in RFC821.
Internal communications between Exchange Servers (2000 and later) over SMTP encode the message in S/TNEF (Summary TNEF) format. The conversion between the format needed by the end client on the internet is performed on the last Hub Transport server before final delivery, and when the Hub Transport role of an Exchange Server is about to deliver the message to a mailbox role server, the message is converted to MAPI format for storage.
S/TNEF differs from TNEF in that it is 8-bit (not 7-bit for TNEF) and does not contain a plain-text portion.
Decoding
Programs to decode and extract files from TNEF-encoded attachments are available on many platforms.Multiplatform
- TNEF Parse - Claws MailClaws MailClaws Mail is a free, GTK+-based, open source email and news client. It offers easy configuration and an abundance of features. It stores mail in the MH mailbox format and also the Mbox mailbox format via a plugin...
plugin - LookOut — Mozilla ThunderbirdMozilla ThunderbirdMozilla Thunderbird is a free, open source, cross-platform e-mail and news client developed by the Mozilla Foundation. The project strategy is modeled after Mozilla Firefox, a project aimed at creating a web browser...
extension- see also:
- http://lookout.mozdev.org/
- the description and "comments 1 through n" (where n is at least 132) -- (over 10 years' worth of comments) -- at the Mozilla BugzillaBugzillaBugzilla is a Web-based general-purpose bugtracker and testing tool originally developed and used by the Mozilla project, and licensed under the Mozilla Public License....
entry for "bug no. 77811"
- Tnef — Evolution plug-in
- fentun Freeware decoder
- WiresharkWiresharkWireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocol development, and education...
— Version 1.2 and later can open and dissect winmail.dat files, although it is not useful as a mail reader
Unix-like/POSIX command-line
- yTNEF — GPLGNU General Public LicenseThe GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....
TNEF extractor from the POSIXPOSIXPOSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...
command-line, designed specifically for reading winmail.dat - TNEF — GPLGNU General Public LicenseThe GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....
TNEF extractor from the POSIXPOSIXPOSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...
command-line - KTNEF — GPLGNU General Public LicenseThe GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....
TNEF extractor for KDEKDEKDE is an international free software community producing an integrated set of cross-platform applications designed to run on Linux, FreeBSD, Microsoft Windows, Solaris and Mac OS X systems...
Mac
- Klammer - Shareware for Mac OS XMac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
, available on App store; also supports MSG files - TNEF's Enough — Freeware decoder for Mac OS 9Mac OS 9Mac OS 9 is the final major release of Apple's Mac OS before the launch of Mac OS X. Introduced on October 23, 1999, Apple positioned it as "The Best Internet Operating System Ever," highlighting Sherlock 2's Internet search capabilities, integration with Apple's free online services known as...
/XMac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems... - tnefDD — Free GPL'd decoder with drag-and-drop functionality for Mac OS XMac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
- TNEF MacPorts version of the TNEF command-line decoder Mac OS XMac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
- Letter Opener (previously known as OMiC) — Shareware, plugin for Apple Mail
iPhone and iPad
- Winmail File Viewer — Paid Universal app for the iPhoneIPhoneThe iPhone is a line of Internet and multimedia-enabled smartphones marketed by Apple Inc. The first iPhone was unveiled by Steve Jobs, then CEO of Apple, on January 9, 2007, and released on June 29, 2007...
, iPod TouchIPod TouchThe iPod Touch is a portable media player, personal digital assistant, handheld game console, and Wi-Fi mobile device designed and marketed by Apple Inc. The iPod Touch adds the multi-touch graphical user interface to the iPod line...
and iPadIPadThe iPad is a line of tablet computers designed, developed and marketed by Apple Inc., primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content. The iPad was introduced on January 27, 2010 by Apple's then-CEO Steve Jobs. Its size and...
to open winmail.dat attachments - Klammer - open EML, MSG and Winmail.dat files - Paid Universal app for the iPhoneIPhoneThe iPhone is a line of Internet and multimedia-enabled smartphones marketed by Apple Inc. The first iPhone was unveiled by Steve Jobs, then CEO of Apple, on January 9, 2007, and released on June 29, 2007...
, iPod TouchIPod TouchThe iPod Touch is a portable media player, personal digital assistant, handheld game console, and Wi-Fi mobile device designed and marketed by Apple Inc. The iPod Touch adds the multi-touch graphical user interface to the iPod line...
and iPadIPadThe iPad is a line of tablet computers designed, developed and marketed by Apple Inc., primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content. The iPad was introduced on January 27, 2010 by Apple's then-CEO Steve Jobs. Its size and...
with in-app purchase to provide functionality - WinDat Opener - Paid app for the iPhoneIPhoneThe iPhone is a line of Internet and multimedia-enabled smartphones marketed by Apple Inc. The first iPhone was unveiled by Steve Jobs, then CEO of Apple, on January 9, 2007, and released on June 29, 2007...
, iPod TouchIPod TouchThe iPod Touch is a portable media player, personal digital assistant, handheld game console, and Wi-Fi mobile device designed and marketed by Apple Inc. The iPod Touch adds the multi-touch graphical user interface to the iPod line...
and iPadIPadThe iPad is a line of tablet computers designed, developed and marketed by Apple Inc., primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content. The iPad was introduced on January 27, 2010 by Apple's then-CEO Steve Jobs. Its size and... - Letter Opener — Free Universal app for the iPhoneIPhoneThe iPhone is a line of Internet and multimedia-enabled smartphones marketed by Apple Inc. The first iPhone was unveiled by Steve Jobs, then CEO of Apple, on January 9, 2007, and released on June 29, 2007...
, iPod TouchIPod TouchThe iPod Touch is a portable media player, personal digital assistant, handheld game console, and Wi-Fi mobile device designed and marketed by Apple Inc. The iPod Touch adds the multi-touch graphical user interface to the iPod line...
and iPadIPadThe iPad is a line of tablet computers designed, developed and marketed by Apple Inc., primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content. The iPad was introduced on January 27, 2010 by Apple's then-CEO Steve Jobs. Its size and...
with in-app purchase to provide functionality
Microsoft Windows
- Winmail Opener Freeware decoder
- Winmail.dat Reader Freeware easy-to-use decoder
- tnef2win Freeware decoder
- Free File Viewer Freeware decoder
Online
- tud.at service — Web service and GPLGNU General Public LicenseThe GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....
licensed PHPPHPPHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
script for reading attachments in winmail.dat files - www.winmaildat.com - Another online winmail.dat extractor which allows to upload up to 5MB
- the-computer-site.com - converts your winmail.dat file to a zip file.
Software libraries
- JTNEF — GPLGNU General Public LicenseThe GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....
Java TNEF package - POI-HMEF - Java library of the Apache POI project
- MVCOM - Commercial COM Component to parse TNEF
- Convert::TNEF -- TNEF library written in PerlPerlPerl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
- pytnef library — TNEF access library written in PythonPython (programming language)Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
, licensed under LGPLGNU Lesser General Public LicenseThe GNU Lesser General Public License or LGPL is a free software license published by the Free Software Foundation . It was designed as a compromise between the strong-copyleft GNU General Public License or GPL and permissive licenses such as the BSD licenses and the MIT License...
External links
- Microsoft Support:
- "How e-mail message formats affect Internet e-mails in Outlook" - How to disable TNEF in Outlook 2002 and 2003
- "Description of Transport Neutral Encapsulation Format (TNEF) in Outlook 2000" - How to disable TNEF in Outlook 2000
- "How to configure Internet e-mail message formats at the user and the domain levels in Exchange Server 2003" - Includes instructions on disabling TNEF
- Other:
- Online converter for winmail.dat / ATT0001.dat email attachments: winmaildat.com
(by t-reinhardt.ch)