Iphone - Inviare posta e rispondere da più account registrati nell'account gmail

- Tap Settings on the iPhone Home screen.
- Go to Mail, Contacts, Calendars.
- Choose Add Account... under Accounts.
- Select Other.
- Enter your name under Name.
- Now enter the email address you want to use under Address.
- Tap a random string under Password.
- Optionally, change the account's name under Description.
- Tap Save.
- Go to the POP tab.
- Enter "g" (or any other string) for Host Name under Incoming Mail Server.
- Enter "g" (or, again, anything else) for User Name under Incoming Mail Server.
- Now enter "smtp.gmail.com" for Host Name under Outgoing Mail Server.
- Tap your Gmail user name (what precedes "@gmail.com" in your Gmail address) for User Name under Outgoing Mail Server.
- Enter your Gmail password for Password under Outgoing Mail Server.
- Tap Save.
- Now tap No in the Cannot Connect Using SSL alert asking you to try setting up the account without SSL.
- Tap Save again.
- Tap Save yet again.
- Tap the newly set up account under Accounts.
- Delete the text in all fields under Incoming Mail Server.
- Press the Home button.
- Make sure the new account is checked for new mail only manually.

You can now choose the desired email address when replying in Gmail or sending a new message. From time to time, go to the secondary Gmail accounts' Sent folders in iPhone Mail to delete sent emails (they are stored in Gmail's Sent folder automatically).

Fonte: http://email.about.com/od/iphonemailtips/qt/gmail_multiaddr.htm