When you are creating invoices, there is an option to send them directly from the toolkit. After you have created approved you invoice, you can then email it to your customer

The first way to do this is to hit "Approve and send" on a draft invoice

You'll be shown a pop-up with the sending details, which you can edit. Then hit "Approve and send" to sent the email

If the invoice was already approved, or you want to resend it later, open the invoice and hit the "Send" button

You can edit the recipient details. You can also add CCs

If you want to check how the email will look before sending, you can just click on "Preview PDF" to review.

If you want to share the PDF from your own email, hit "Download PDF", and then you can just send it as an attachment

How to send or resend an invoice