Purchase Order PDF that is sent to supplier after approval to be sent from a custom email address

Summary:

The business requirement is that, whenever a purchase order is approved, the supplier is to be sent an email with the PO PDF and the 'FROM' is to be set as a custom email address and not the automatically generated workflow email address.

Please advise on how to achieve this.

Content (please ensure you mask any confidential information):

The business requirement is that, whenever a purchase order is approved, the supplier is to be sent an email with the PO PDF and the 'FROM' is to be set as a custom email address and not the automatically generated workflow email address.