Hello! When I send a payment receipt to customer, the receipt is not attaching to the email. Any ideas why? And how to remedy?

Hello, gmartin1. 

To attached the payment receipt when emailing them to your customers, you need to modify and set it up to add the PDF to your sales forms. I'm here to guide you with the steps:

1. Open your QuickBooks Online account, then select Account and settings from the Gear icon. 
2. Select Sales. Within the Online delivery section, make sure the PDF Attached is ticked.
3. Tap an additional email option under the Additional email options for invoices section.
4. Hit Save, then Done. 

After that, try sending the payment/receipt again. 

For additional reference about emailing and customizing forms in QuickBooks Online, you can check out these articles:   

• Add, customize, or remove logos on sales forms.
• Customize invoices, estimates, and sales receipts in QuickBooks Online. 

The comment section is always available if you have additional questions about attachments. I'll be here to help you further. Have a great day and stay safe!