The below configurable variables (accessed via Admin>Config) are available to control the text that is shown in the Purchase Order Email Subject Line, the Purchase Order Email Attachment File Name, the Invoice Email Subject Line and the Invoice Email Attachment File Name.
PURCHASE_ORDER_EMAIL_SUBJECT
PURCHASE_ORDER_EMAIL_ATTACHMENT_FILENAME
INVOICE_EMAIL_SUBJECT
INVOICE_EMAIL_ATTACHMENT_FILENAME
For example, if set up as below;
PURCHASE_ORDER_EMAIL_SUBJECT = “Purchase Order {$PurchaseOrder.PurchaseOrderNumber}”
PURCHASE_ORDER_EMAIL_ATTACHMENT_FILENAME = ‘purchase-order-{$PurchaseOrder.PurchaseOrderNumber}.pdf’;
INVOICE_EMAIL_SUBJECT = “Invoice {Invoice.InvoiceNumber}”
INVOICE_EMAIL_ATTACHMENT_FILENAME = ‘invoice-{Invoice.InvoiceNumber}.pdf’