So, I’ve got a couple of email addresses under a single username/password combination, let’s call them firstname.lastname@example.org and email@example.com (in actuality it’s more like firstname.lastname@example.org, email@example.com, firstname.lastname@example.org and email@example.com but two should suffice). I was trying to figure out how to allow Mail.app (the email application that ships with OSX) to send as any of these email addresses (you might call these “aliases” or “outbound email addresses”). I tried to configure a new account that wasn’t configured with an inbound server, but that didn’t work, so I asked Google:
And Google spoke (in the voice of this page) saying: You simply comma-delimit multiple email addresses when configuring an account and they all become available in the “account” dropdown when composing email. A very clean solution (if not terribly intuitive or discoverable). It’s exactly the sort of thing a novice email user would never need to know and an advanced user would know to (eventually) google for!