You can create invoice email templates in the Email Settings screen (Settings > Company). You have the option to pre-fill your invoice emails with details such as subject, default message, and support smart fields. Check CORE Help Center for details.
Invoice email templates support smart fields such as {ClientName}, {InvoiceNumber}, {BillingContact}, etc. The {BillingContact} smart field dynamically populates the primary billing contact associated with each invoice, ensuring the correct contact name appears in both individual and batch invoice emails.
If needed, you can change the email address or ID that appears in the address block of invoices in the Settings > Company screen. Check CORE Help Center for details.