changing from address in apple mail
I would like to be able to change my "From" address on a per email basis. I have added an email address amazon@mydomain.com via preferences which I then can select from the "From" drop down list when I compose an email. However, although my Sent folder shows the email having been sent from amazon@mydomain.com it arrives at a 3rd party as myname@gmail.com which is my usual email address.
MacBook Pro, macOS Sierra (10.12)