When overridden in a derived class, the property gets or sets a value that indicates the date and time by which a reply to the message is expected.
Assembly: Microsoft.Exchange.Data.Transport (in Microsoft.Exchange.Data.Transport.dll)
Setting the property of a Multipurpose Internet Mail Extensions (MIME) message to a value of DateTime.MinValue removes the header from the message. When the value of the property is set, the EmailMessage object determines the time zone to be either current or coordinated universal time (UTC), depending on the DateTimeKind of the value.
When you set the value of the property by using an instance of the DateTime structure that does not specify DateTimeKind, the property assumes that the DateTime instance represents local time.