While we'd love to help you eliminate paper from your business entirely, sometimes you just gotta get someone a hard copy for their file drawer. Here's how you can email your customer a PDF of an estimate or invoice.
If you want to take advantage of this option, there are two places you can enable it. The first is on the Send Estimate or Send Invoice screen, right under the optional message.
Check that box before hitting the Send Estimate or Send Invoice button, and your PDF will be sent right along with it.
If you want to make this the default, just go over to Settings > Messaging Templates. Choose the Estimate Email or Invoice Email tab. You'll see a new checkbox at the bottom:
Selecting that option will attach a PDF copy every time you send the document (unless, of course, you uncheck the box on the Send screen).