Original sentence: 400 protocols, they try to map this internal model onto those protocols in a way that can be reversed if the ultimate recipient is also running Outlook or Exchange.As a workaround, numerous tools for (partially) decoding TNEF files exist.If the recipient is Outlook/Exchange it can simply discard the incomplete outer message and use the encapsulated data directly, but if the recipient is any other program, the message received will be incomplete because the data in the TNEF attachment will be of little use without the Microsoft software for which it was created.Outlook and Exchange Server internally handle messages, appointments and all other items as objects in a data model which is derived from the old proprietary Microsoft Mail system, the Rich Text Format from Microsoft Word and the complex OLE general data model.This focus on the possibility that emails and other items will ultimately be converted back to Microsoft Mail format is so extreme that if Outlook/Exchange cannot figure out a way to encode the complete data in the standard format, it simply encodes the entire message/item in a proprietary binary format called Transport Neutral Encapsulation Format (TNEF) and sends this as an attached file (usually named "winmail.When these programs interface with other protocols such as the various Internet and X.dat") to an otherwise incomplete rendering of the mail/item
Edited sentence: In addition, no e-mail clients other than Outlook support it natively, although numerous tools for decoding TNEF files exist.It is usually present in a form of attached files winmail.Outlook uses a proprietary attachment format called Transport Neutral Encapsulation Format (TNEF) when editing messages in Rich Text Format, using embedded (OLE) documents or Outlook-specific features.TNEF is not RFC compliant.These files may also contain any regular files attached to the message.dat in the message.dat or win