Date of the mail message (optional).
If this property contains a non-empty string, then a Date SMTP header is created and attached to the message. If it is an empty string, then the date information is added by the mail relay(s) the message goes through.
Special case: if this property is set to the special value "*", a Date SMTP header reflecting the current date and time is generated when MessageHeaders is computed and the message is sent. This is the default behavior of the component
RFC 822 contains detailed date format specifications. An example of a valid date is "Fri, 1 Mar 96 21:24:52 EST".
This property is not available at design time.