With Billtobox you can send invoices to your customer's email address.
Go to the Accounts receivable menu
Import an invoice (or create one using the DIY invoice creation tool)
You now have an invoice in Draft status
Click on the draft invoice to go to the details page and choose email from the Channel's dropdown menu
Right under that field, you'll find the email address to which the invoice will be sent.
You can also:Include a payment button (you'll first need to activate the payment services)
Choose to attach the UBL and/or PDF file(s)
Add a personal message that'll appear in the email sent to your customer
Tip: for customers to whom you will regularly send invoices, you can go to the customer's file and set up email as the default delivery channel.