I'll guide you on how you can customize the subject line of your Bill Payment Stub, User90502.

Customizing email templates will help you effectively communicate with your vendors. You can create an template and edit the subject line from there. To get started, make sure to sign in as admin and follow the steps outlined below:

1. In the Edit menu, select Preferences.
2. Choose the Send forms menu, then the Company Preferences tab.
3. Select Email in the Delivery Method Default dropdown.
4. In the Email Templates dropdown, pick Bill Payment Stub.
5. Click on Add Template and enter a template name.
6. Update the subject line.
   
7. Click Save and then OK.

Additionally, you can utilize the template by ticking the Default box beside the Bill Payment Stub field if you want to use this moving forward.

Also, learn about the Accounts Payable workflows you can use in QuickBooks Desktop so you'll understand the end-to-end process of procuring the payment transactions. I've added this article for more details: Accounts Payable Workflows in QuickBooks Desktop.

Post your comment if you have any questions about customizing email templates. We're here to get you covered. Have a nice day ahead!