Hello Graffiks-ca,
Welcome back to the QuickBooks Community. I hope things have been going well for your business and I love how you're looking to integrate QuickBooks Online's form email option with your company's payment page. I can see how that would make things super simple for your customers when it comes time to pay their invoices. I'll go over this with you.
There are a few ways to edit QuickBooks Online's emails that get sent out with forms, such as through the account settings or through the custom form styles. As I'm sure you know, these sections give you the opportunity to change the text for the email and some other sending options. At this time, there isn't a way to change the email to an HTML or coding format to be able to embed code for buttons or other such things, but that's a great idea! I recommend sharing your thoughts about that with our product development team via the send feedback feature outlined here: How do I submit feedback?
In the meantime, you can consider copying and pasting the URL to your company payment page in the email body. I know this might not be quite as professional looking as a button, but this will still show your customer where they can go to pay with a clickable link to do so.
I hope you have a great rest of your week.
