Open Messaging
and select Options > Settings > E-mail.
To create or edit mailboxes, open Mailboxes. Select Options > New mailbox or open an existing mailbox from the list.
To change the mailbox used by default for sending e-mail, scroll to Mailbox in use and select Change. Select the new mailbox.
To change the mailbox used by default for sending e-mail, scroll to Mailbox in use and select Options > Change. Select the new mailbox.