What is the "from" email address on invoices?

Thanks for posting here, @maevehelenadams-.

When emailing an invoice from your QuickBooks Self Employed account, the From email field indicates the sender's email address. This is the email address associated with your QBSE account. 

For more info, see this article: Create invoices in QuickBooks Self-Employed.

I also encourage you to visit our QuickBooks Help page so that you can browse articles or even questions answered by QuickBooks experts. This will help you with your accounting tasks.

Feel free to post again here if you need more help managing your QuickBooks emails. I am always here to help. Have a good one