Use these placeholders in your subject and body to personalize emails. Surround placeholders with curly braces: {placeholder_name} Placeholder Description Example Output {customer_name} First and last name of customer/client John Smith {customer_email} Customer email address (used for sending) john@client.com {invoice_number} Invoice number/reference INV-2025-001 {amount_due} or {invoice_amount} Total invoice amount with currency (Multi-Currency formatted if plugin active) $1,250.00 or €1,137.50 {due_date} Invoice due date formatted per WordPress date settings March 15, 2025 {days_until_due} Number of days remaining until due date (not applicable to overdue, shows 0) 0 (in overdue phase) {days_overdue} Number of days past due date (primary metric for Overdue phase) 7 (7 days late)