WorkGuru lets you email approved invoices as a batch.

  1. From the Invoices Dashboard, select the approved tab, and then either select all, or just specific invoices to send to your clients. 
  2. From the bottom of the invoices dashboard, select invoice template you want to send.
  3. Click the Bulk Send Invoices button to send the selected invoices to the default email address of the billing contact for each invoice.