In B1P&D you have the option to specify the "From Email" in the SMTP window:
You will find that in most cases you will not be able to change the from email to something different than the username. This is due to how the SMTP at the receiver is setup.
Normally SMTP servers does not allow you to "impersonate" other email addresses as this would then be possible to misuse for phising.
Technically we send the from email to the SMTP server but if it choose to ignore it or not is controlled by the SMTP.