No, there is no such property or method. You may find the
Importance property of the MailItem class helpful.
Also you can use the MarkAsTask method of the MailItem class which marks
a MailItem object
as a task and assigns a task interval for the object. Then you can use the Assign method of the TaskItem class. This
method allows a task to be assigned (delegated) to another user. You must create a task before you can assign it, and you must assign a task before you can send it. An assigned task is sent as a TaskRequestItem object.