Actually the Date field is data that the user enters by way of when they
composed the message, not when they sent it. That is, even if you use a
scheduling add-on or Exchange to send your e-mail at a later time, the
date shown in your e-mail is when you composed it, not when it got sent.
The mail host will prepend its Received header that shows when it got an
e-mail. So it depends on "what" date the OP is asking about.
