LazyMAPI

MAPI Properties

MAPI Property: PR_CONVERSATION_TOPIC, PR_CONVERSATION_TOPIC_A, PR_CONVERSATION_TOPIC_W
Description: Contains the topic of the first message in a conversation thread.
Property ID: $0070
Property type: PT_STRING8, PT_UNICODE
Area: General messaging

Remarks:
A conversation thread represents a series of messages and replies. These properties are set for the first message in a thread, usually to the PR_NORMALIZED_SUBJECT (PidTagNormalizedSubject) property. Subsequent messages in the thread should use the same topic without modification.
The PR_CONVERSATION_INDEX (PidTagConversationIndex) property indicates the order relationship between subsequent messages and replies. Its use is optional, even if these properties are set.
A message store provider has the option of assuring that these properties are always set on incoming or outgoing messages. If these properties are already set they should not be altered. If not, they can be set to PR_NORMALIZED_SUBJECT. Any action should be taken before IMAPIProp::SaveChanges is called.