It used to be possible to configure your Gmail inbox to send email as
firstname.lastname@example.org by simply redirecting that email address to your inbox, and then sending through a confirmation email.
But since a recent change, that's not possible anymore and you now need to set up a full SMTP server.
My question is, what is the recommended technique/service to use to regain the previous functionality? Use a third-party SMTP provider? If so, which one?