- Log in to Gmail at http://mail.google.com.
- Open the message.
- Click Reply, Reply to all, or Forward.
- Click change next to your address in the From field to select the address you'd like to use to send the message.
- Compose and send!
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Tip: Once you've added more email addresses to Gmail, set your other accounts to auto-forward your messages to Gmail. That way, you can easily manage your other email accounts from Gmail.