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MS-TNEF files

Posted on 1998-06-09
Medium Priority
Last Modified: 2006-11-17
Is there a plug-in available that would allow me to read MS-TNEF?  I have rec'd several of these files via e-mail.
Question by:wconner

Author Comment

ID: 1820555
Adjusted points to 100

Expert Comment

ID: 1820556
What are MS-TNEF files?

Accepted Solution

stevemiller earned 200 total points
ID: 1820557
This link explains in link what MS-TNEF files are and how to read them:


In short-
Problem:When I send mail to an Internet mailing list, its members complain that my messages contain big binary
attachments. What's happening? How can I get rid of these?

Answer:Either intentionally or accidentally, you have been sending messages in Microsoft rich text format to recipients using mail programs that cannot
decipher this format.

When Exchange thinks that it is sending mail to another Exchange user on the Internet, Exchange (more properly, the Internet Mail message
service provider) encodes the message, along with attached files, embedded OLE objects, and their associated icons, into a special data block
called the TNEF (pronounced tee-neff) block. This block encapsulates the complete original content of the Exchange message, so that the
message arrives at its destination with all proper formatting intact, including boldface, underlining, fonts, and colors. Otherwise, Exchange formats
the message in an Internet-standard fashion, discarding all rich text attributes and ensuring that all attached files appear as standard attachments.

The problem arises when people not using Exchange or Outlook receive a message in the TNEF format: instead of seeing a formatted message,
they see a big chunk of UUENCODE data if the sender used UUENCODE format, or a MIME body part application/ms-tnef if the sender
used MIME. Depending on which mail program they use, they may either see a long sequence of hexadecimal digits, or they may see an attached
binary file named WINMAIL.DAT.

Exchange specifies whether it emits TNEF or not as a property of the recipient, appearing as a field on the property page of the underlined
recipient object within an Exchange To or Cc field. (The underline in the To field means that Exchange has recognized the name, and associated
an address and other information with it.) To see this recipient property page, double-click the underlined recipient: when using either the Internet
Mail provider or Microsoft Exchange Server, the popup that appears should include a check box labeled Send to this recipient in Microsoft
rich text format. If this check box is set, Exchange/Internet Mail will use a TNEF block when sending messages to that user; otherwise, it will
strip the rich information and send plain text. The sender can also set and clear this flag on entries in the Personal Address Book. Should the
sender address a message using an entry from the Address Book, Exchange will use the setting of this flag from that entry.

Never set this check box if you suspect that your recipient isn't using Exchange or Outlook, or if you are sending mail to an Internet mailing list.
Otherwise, your mail will include binary garbage.

Unfortunately, even if you never set this checkbox, there are several ways to send Internet mail messages in TNEF format by accident.

     If you address the message by typing a literal name@domain.xxx SMTP address, or by entering the address in Exchange's explicit
     one-off format - i.e., by typing [SMTP:name@domain.xxx] - and you use the version of Microsoft Exchange released with retail
     Windows 95 (as opposed to Windows Messaging, or the version released as the client of Microsoft Exchange Server), the entry will have
     its Send to this recipient in Microsoft rich text format checkbox set by default.
     If you address the message by typing a name and letting the system pick an entry from your Personal Address Book, and that address
     book entry specifies Send to this recipient in Microsoft rich text format, then the recipient in the message will, too.
     If you address the message by giving the reply command in Exchange, and the message to which you were replying had an explicit
     RFC822 Reply-To header (such as is the case on many messages arriving via Internet mailing lists), and you use a version of the Internet
     Mail provider prior to the IMEP, the resulting entry in the To field will have its Send to this recipient in Microsoft rich text format
     checkbox set by default. Note that a reply will never reference an entry in your Personal Address Book unless you replace the contents of
     the reply note's To field yourself.

Some workarounds:

     If you are using the original version of retail Windows 95 Microsoft Exchange, update to a more recent version, such as the Windows
     Messaging update.
     Know the contents of your Personal Address Book, and ensure that you have not erroneously set the rich text flag on any entries therein.
     Use the most recent version of the Internet Mail message service provider. (Note: Microsoft Exchange Server users do not use this
     component, since they send mail to the Internet through a component of Exchange Server.)
     On replies to Internet mailing lists, manually clear the rich text flag, or else replace the reply address with a known entry from your PAB.
     Use my Rich Text Sentry widget, which watches for outgoing Internet messages in rich text format, or install a recent version of Internet
     Idioms and configure it to do likewise.

Microsoft has their own explanation of this phenomenon in the KnowledgeBase article Q136204.

The entire preceding discussion assumes that you are using either the Internet Mail (SMTP/POP3) or Microsoft Exchange Server messaging
service. If instead you are using the Microsoft Mail messaging service, and depending on a Microsoft Mail gateway to carry your message onto
the Internet, you are out of luck, unless you have a gateway clever enough to strip WINMAIL.DAT.


Expert Comment

ID: 1820558
There is a plug-in available for reading ms-tnef MIME content types. It is called fentun and can be downloaded at http://twain.softhome.net/fentun/index.html .  It works well with Netscape Communicator.  This is the only one I have found.

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