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PidTagConversationTopic Canonical Property

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Contains the topic of the first message in a conversation thread.

Associated properties:




Data type:



General messaging

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.

Protocol Specifications


Provides references to related Exchange Server protocol specifications.


Specifies the properties and operations that are permissible on e-mail message objects.

Header Files


Provides data type definitions.


Contains definitions of properties listed as alternate names.