Specifies whether Transport Neutral Encapsulation Format (TNEF) should be included on a message when the message is converted from MAPI to Multipurpose Internet Mail Extensions (MIME) or Simple Mail Transfer Protocol (SMTP) format.

Quick Info

Exposed on: Message objects
Created by: Outlook
Accessed by: Outlook and solution providers
Property type: PT_BOOLEAN
Access type: Read/write


To retrieve the value of this property, first use IMAPIProp::GetIDsFromNames to obtain the property tag, and then specify this property tag in IMAPIProp::GetProps to get the value. When calling IMAPIProp::GetIDsFromNames, specify the following values for the MAPINAMEID structure pointed at by the input parameter lppPropNames:

lpGuid: PSETID_Common
ulKind: MNID_ID
Kind.lID: dispidUseTNEF

dispidUseTNEF only applies when the message is sent from a POP3/SMTP mail account and does not apply when the message is sent by other providers, such as Microsoft Exchange Server.

Under certain circumstances, such as when voting buttons are enabled or an OLE embedded object is attached to a message, Outlook can set dispidUseTNEF to force the use of TNEF.

The PR_MSG_EDITOR_FORMAT property can be used to enforce only plain text , and not TNEF, when sending a message. Because dispidUseTNEF overrides the setting in PR_MSG_EDITOR_FORMAT, an Outlook add-in that wants to force plain text on an outgoing message should also look for dispidUseTNEF and reset it to False. Additionally, the add-in must remove the message features that required TNEF to avoid unusable attachments on the message that is finally sent.

Using the CCSF_USE_TNEF flag when calling IConverterSession::MAPIToMIMEStm to convert an outgoing MAPI message to a MIME stream can also enforce TNEF. This applies even if dispidUseTNEF is not set.

See Also

Constants for Outlook Named Properties