Add Sales Order PO# field on the Item Fulfillment Email – JCurve Solutions

Navigate to Setup > Accounting > Accounting Preferences.
On Order Management tab > Fulfillment section > enable Send Order Fulfilled Confirmation Emails and disable Use Web Site Template for Fulfillment Emails.
Click Save.
Navigate to Setup > Accounting > Customize Fulfillment Email.
On Customization window, insert the code below after {2}

<br> Your Purchase Order#: <%=getCurrentAttribute('salesorder','otherrefnum') %> <br><br>
Click Save.
On Transactions > Sales > Enter Sales Order, create sales order with valid email address and enter value for PO# field.
Click Save on the sales order.
Click Fulfill button from the sales order.
Fill in the mandatory fields in New item fulfillment page.
Then click Save to trigger the email.