Basically the answer is no. The time sent timestamp on your email is put on there by the email server. So unless you have your own email server you can't change the time.
The email server that will set the time is the server Larger computers that include functions for multiple users) that you are connected to that sends and receives e-mail. It will stamp the mail when it sends it after receiving it from you.
Basically when you send e-mail it goes to an email server that then transmit it toward the server that has the account you are sending to. Your email sits on the receiving server until you bring it to your machine.
A way to picture how this works is to compare it to the postal service. You have no control on the postmark time and date stamp. When you mail a letter it is like you pressing send on the email. Then at the post office they stamp the postmark time on it as they prepare to handle the letter. Likewise as your email arrives at the email server as the server prepares to process it the date and time is put on the email.
Then the letter goes to the post office that has the mailbox you were sending to. Until the individual comes and opens their box the mail sits there. This similar to your email arriving at the destination.
You could end up with time stamps tat are significantly different form the time sent if you live near a time zone line and your server is on the other side, the server you use may be located several states away in a different time zone and lastly the time could be wrong on the email server.
Thanks Britt for the question.