If your account is past due, Yahoo! Small Business will attempt to alert you in several ways:

Figure 1: The "Manage My Services" page, with the "Manage My Services" button (highlighted) showing an alert.

Figure 2: Clicking the "Manage My Services" button (highlighted) when an alert appears will open a menu that includes an account status message — in this case, an account-overdue warning.

Figure 3: When your account is suspended, the "Manage My Services" menu (highlighted) opens automatically to show your account status.
The email messages will continue to be sent, and the alert messages will continue to appear in your account upon sign-in, until you have updated the credit card information for your account and Yahoo! is able to charge your credit card to bring your account into good standing.