Batch Process for Printing Invoices
You can print or email invoices in groups or batches by going to Income -> Reports -> Billing -> Reprint Invoices.
You can select certain invoices to include in the batch in the Select Specific Invoices To Print section.
After clicking Next you will see a list of invoices that can be emailed or combined into a single PDF file for printing or archiving.
Click Send Notices to individually email out each invoice on the page.
You can add an invoice email template to use by going to Admin -> System -> Mail Templates. Select Invoice as the type when making a new template.
Set the default email template to use by going to Admin -> Billing -> Company Options -> Defaults -> Invoicing -> Default Automated Invoice Email Template. This setting can be overridden per customer by choosing a Default Automated Invoice Email Template on the customer edit page.