Transport Neutral Encapsulation Format

TNEF ( Transport Neutral Encapsulation Format ) is the name for a proprietary, by Microsoft in their e -mail program Microsoft Outlook and Exchange implemented file format for attachments ( attachments ). It contains both " descriptive structures " and the actual attachment, embedded in the e -mail. Attachments in this format often automatically get the filename winmail.dat or win.dat.

Peculiarities and problems

Since this is a proprietary format that is perhaps most obvious problem is that a receiving e-mail program does not understand the format. While most programs are now (as of 2013) to be able to handle this kind of attachments, but used eg not everyone always have the latest versions. Especially in regard to automatic processing of emails but it is more likely that problems occur. Since usually no end user applications, but modules are used here for the various programming languages, it often happens that a " unpacking " of TNEF attachments will simply overlooked.

It may happen that someone re- sent such an attachment as a file with a different mail program, or forwards ( possibly under a different file name than the standard name of winmail.dat ), so that the recipient not necessarily initially recognizes that it is such a format concerns.

The problem is, above all, that " descriptive structures " do not really belong in the item that they describe. For the elements that can appear within e- mails (to be), there are already well-defined structures, so just the effect is avoided that one needs certain proprietary software to access the contents of the mail or attached files.

Solutions

One can solve problems with these types of attachments, without having to use Outlook itself:

• In yourself: There are multiple operating system utilities to extract those files into a readable format and save it.
• Request the sender: The use of TNEF can be turned off in Outlook ( in the below linked article in the "Microsoft Knowledge Base " section ).