The PR_SUBJECT property contains the full subject of a message.
The PR_SUBJECT property is recommended on all message objects.
This property is always the full subject text, that is, the concatenation of the prefix and the normalized subject. If there is no prefix, the normalized subject should be the same as the subject. The subject properties are typically small strings of fewer than 256 characters, and a message store provider is not obligated to support the OLE IStream interface on them. The client should always attempt access through the IMAPIProp interface first, and resort to IStream only if MAPI_E_NOT_ENOUGH_MEMORY is returned.
For a report, PR_SUBJECT contains the original message's subject preceded by a string indicating what has happened to the message.