The Accounts list
The Accounts list displays all of your email accounts.
Open the Email app. Tap the Accounts
List icon 
(at
the top of the screen) to display a drop-down list of all of your
email accounts.
Each account in the Accounts list displays the number of unread mail.
Tap an account to view its Inbox.
NOTE
While viewing the combined list of your email messages, default email account messages are indicated. "Default" is displayed beside the account in the Account list menu.