Depending on your plan, you're able to make changes to your customer email notifications.
With custom email notifications you will be able to;
Edit the emails that your customers receive when you send them late fee notifications, including adding text and your logo.
Edit the email subject line of what they receive.
To find the email editor
> Go to the General tab
> Select Use Custom Emails?
Important: When editing the email subject, make sure you include the merge tag {{{original_invoice_number}}}
Important: When editing the email content, make sure you use the ALL of the custom merge tags in the email editor selected in red below;