The Bulk Email Tracking functionality provides you a way to verify that your batch invoices have been sent. This feature needs to be enabled under 
Setup -> Email Settings -> Turn on Invoice Tracking Beta, at the very bottom of the page beneath the Unsubscribe Message.

NOTE: Batches are tracked when invoices are delivered via the Sales/Invoices tab in the Billing module, the Pending Delivery tab in the Billing module, and the Unpaid tab in the Memberships module.

To review your batches:

1. Click Memberships in the left-hand navigation panel
2. Click the Batch Tracking tab.

The Batch Tracking screen will display the following information:

• Batch ID: This can also be used in the communication report for a more detailed view of what was sent
• Batch Name: The subject of the email sent
• Person Who Hit Send
• Time Stamp: When the batch was sent. 
• Status:  Provides the number of invoices that were delivered out of how many were attempted. The system will retry any failures 10 times, then log a failure.
• Exception: Provides a clickable icon that will open a dialog to list the contacts that did not have a successful delivery.