The easiest way to mark a drafted invoice as sent is to act as if you are sending it via URL. In other words, all you need to do is go through the same steps as sending it via URL, since it will automatically mark your invoice as "sent".

To do this, just click "Send Invoice" to open the invoice sending modal.

Then, select "Send via URL" to confirm that you would like to send your invoice outside of Bonsai. Once you click "Continue", you will be shown your secure invoice link and your invoice will now be considered sent.