PR_SUBJECT, PR_SUBJECT_A, PR_SUBJECT_W
Contains the full subject of a message.
These properties are recommended on all message objects.
These properties are 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. A message store or transport provider uses both these properties and PR_SUBJECT_PREFIX (PidTagSubjectPrefix) properties to compute the normalized subject using the rule described under PR_NORMALIZED_SUBJECT (PidTagNormalizedSubject).
The subject properties are typically small strings of fewer than 256 characters, and a message store provider is not obligated to support the 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, this property contains the original message's subject preceded by a string indicating what has happened to the message.