Apple Mail has no easy configuration for multiple identities. It is possible to use multiple identities for sending mail, but the configuration is a bit weird! (tested this with Lion…)
In Apple Mail go to:
- Menu “Mail”
- Select “Accounts”
- Select your mail account on the left side of the screen
- Select “Account information” on the right side of the screen
Now in the field “Email Address:” enter the email addresses you want to use separated with a comma…. !
Now you will get a dropdown box in your “New mail” form with the mail addresses you entered. You can select the address you want to send from 🙂
It is a strange way to configure this, but it works.
(This appears to be a documented feature! See the Apple doc on this: http://support.apple.com/kb/ta23485 )