Note: You can control whether or not Mail will show on your IntelliScreen via the View Layout

Managing Multiple Email Accounts
While there is only one mail content window in IntelliScreen, the mail content area can allow you to scroll through multiple email accounts. The most effective way to do so is setting the mail accounts to "Only New Messages".

You can select which mail accounts to show by tapping on the mail account.

Note: You must receive email to the account before you may select the account.

You can reorder your mail accounts by pressing on the right hand side of the account and sliding the account up or down.

Tap to Check Mail
For non-push email accounts, you can enable Tap to Check Mail. Tap to Check Mail will display a refresh icon on your IntelliScreen to request a mail fetch. This is the same functionality as going into the Mail.app and pressing the refresh button.

If you enable tap to check - your Mail content area will show even if you have it set to New1 or New2 in the View Layout screen. While the mail content area will be displayed to allow you to "Tap to Check", it may not show any messages depending on your Mail display preferences (ie, Only New Messages and the Mail content area is set to "New1").

Tap To Check will only enable if you have your mail fetch time set to an interval other then manual (Under Settings --> Fetch New Data -> Fetch). 

On Lock Screen: Jumping to Next Account
You can jump to the next account in the Mail content area by double-tapping the mail account.