The formal requirement is to list positions in the manner dictated by the ESDS. Thus, if the ESDS office indicates you need a contact e-mail, then you should include a contact e-mail. If the ESDS office provides no instruction in this regard, then you have more discretion.
You can use this OFCCP audit checklist to ensure you're doing what is required to maintain OFCCP's regulations including VEVRAA, Section 503, and EO 11246. Or request a demo to streamline your compliance and recruiting efforts.