Hello Mike,
When you create an estimate, you can select 'Email notification when saving?'. This will send out the estimate to any contacts under the customer that does not have 'Opt Out Of Billing?' checked. To figure out what contacts have the option checked, go to the Customer edit page and choose the contact in question. (Customers and Contacts List -> Go To… Customer -> Contacts tab -> Choose Contact). You will see the 'Opt Out Of Billing?' option.
You can also do customization if the estimate has to be sent to a certain contact(s) that can not be managed by the 'Opt out of billing?'.
Thanks John for posting and letting Mike know it is possible.
- Greg