You can email 6 types of sales transactions to your customers from QuickBooks Online. Forget about hassling with postage and envelopes.
Your customers may notice that when you send them a transaction the return email address is listed as email@example.com. This is the result of a feature within that allows you to message your customer back and forth directly within the invoice in QuickBooks Online, making it easy to see what your customer has said and message them back all without leaving QuickBooks Online.
If you pull up the invoice, you'll see a section at the bottom that says Activities. This will show you exactly when the invoice was sent, when the customer viewed it and any messages that have been sent back and forth. To send them a message simply put it into Write a message about this invoice box and the customer will receive an email letting them know you've sent them a message.
Although this feature is in place, you and your customer can still email each other through the actual email that is sent. Your customers can still reply to the actual email and once they click reply it will direct the email to your email address. If you would prefer your customers use this method to contact you we suggest putting a message on the "Body" portion when sending the invoice that tells them to reply directly from the email rather than using the messaging feature once they open the invoice link. You'll see this section on the email preview screen after you click Save and Send.