The email2:ConversationId element<8> is a required element that specifies a unique identifier for a conversation. It is defined as an element in the Email2 namespace.
The value of this element is a byte array data type, as specified in [MS-ASDTYPE] section 2.6.1.
The client MUST NOT change the email2:ConversationId element value. The server returns a Status element value of 6 in the Sync command response ([MS-ASCMD] section 126.96.36.199) when the email2:ConversationId element is included within a Change element ([MS-ASCMD] section 188.8.131.52) in a Sync command request.
For more details about conversations, see [MS-ASCON].