DocumentMimePartialMessageTotalParts Property

If IsMimePartialMessage is true, then property holds the total number of message parts. It is not always guaranteed that each message part will have the total parts set in MIME 'ContentType' header value, often it is just the first or last message part that has this value set.

[DataMemberAttribute]
public int? MimePartialMessageTotalParts { get; set; }