The following configurable variables accessed via Admin>Config are designed to control the text that is shown in the:
Purchase Order Email Subject Line – PURCHASE_ORDER_EMAIL_SUBJECT
Purchase Order Email Attachment File Name – PURCHASE_ORDER_EMAIL_ATTACHMENT_FILENAME
Invoice Email Subject Line – INVOICE_EMAIL_SUBJECT
Invoice Email Attachment File Name – INVOICE_EMAIL_ATTACHMENT_FILENAME
For example if set up as below:
PURCHASE_ORDER_EMAIL_SUBJECT = “Purchase Order {PurchaseOrder.PurchaseOrderSupplier} {$PurchaseOrder.PurchaseOrderNumber}”