An information store is known as RTF-aware if it keeps the body and the RTF text of a message synchronized. The server information store and the offline folder store (OST) are RTF-aware and the personal folder store (PST) is not RTF-aware.
The MAPI RTFSync function synchronizes PR_BODY and PR_RTF_COMPRESSED, ensuring that the rich text format body of a message matches the plain text body. You call this function before reading the RTF body and after modifying the RTF body. This is necessary for when working with the PST. For the server information store and the OST, you do not need perform this extra step. For information about RTF-awareness in message stores, see the MAPI Programmer's Reference.