_MailItem.ConversationID Property
Office 2010
Returns a String (string in C#) that uniquely identifies a Conversation object that the MailItem object belongs to. Read-only.
Assembly: Microsoft.Office.Interop.Outlook (in Microsoft.Office.Interop.Outlook.dll)
This property associates items with a conversation. These items and the conversation all have the same value in their ConversationID property.
This property corresponds with the MAPI property PidTagConversationId.
If the MailItem object is created in a version of Microsoft Outlook earlier than Microsoft Outlook 2010, or if Outlook is running in online mode against a version of Microsoft Exchange Server earlier than Microsoft Exchange Server 2010, this property returns the same value as the ConversationTopic property.
