2.1. Check Your Mail

To check your mail, tap the Mail icon on your Home screen. By default, if Mail is configured to check for messages automatically (see Fetch/Push Options), or if you’ve previously launched Mail and retrieved email messages, a red badge on the Mail icon shows how many unread messages you have before you even open the app. Opening the app causes it to log in to your email account(s) and immediately check for new messages, which includes any that arrived since the last scheduled fetch.

Note:

All for one: The badge shows the total number of downloaded unread messages in the Inboxes of all your email account. The badge doesn’t show unread messages in other mailboxes.