Our Accounts Receivable Department are struggling to match this information with their statements everytime we get to many orders. I've being reading API pages in Shopify and how to customise order confirmation email template and I can't find the code. Support Service don't support code questions. If anyone has encounter this problem and has the solution this will be a lifesaver for us.
I don't believe that information is accessible via Admin API or Liquid transaction object. The PO# is inputted by the shopper correct? If that's the case Accounts Receivable needs to know the PO# and the Order #. Am I still correct here? If so, your payment gateway has an API. We can retrieve the PO# using that API and send off a separate email using a custom app. If you need the PO# in the order confirmation email sent to your customer it would be the same idea only you would disable Shopify's email and subscribe to Orders Paid webhook and allow the custom app to send those emails.