There are a number of ways to send a document by email from within Infusion.
Addresses for recipients must first be setup within the Supplier or Customer for each document type. See instructions here
Directly on creation of the document.
When you process an Invoice or Purchase order the document is sent to the Queued Emails to be sent from Admin / Queued Emails.
By Right Clicking on the Invoice or Purchase Order from the Manage Screen there are 3 email options.
Please select see detailed instructions by selecting this link Email Via Right Click
Email Now (via Queue)
Email (local Email Application)
From the Print/Preview Screen
Click the envelope in the top menu of the screen.
This will open your Default Email Program and the PDF is saved as an attachment.