Hi Arjith,
For PO release, we have standard workflow 'WS20000075' provided by SAP. Whenever PO is created, the event 'RELEASESTEPCREATED' would get triggered. There would be a linkage in between this workflow and the said event.
Your functional consultant will configure the release strategy with level of approvals. The standard rule '20000027' will pick the agents to whom the approval mail needs to be sent.
For mail body, customize the standard task in the above workflow according to your client requirement.
Best Regards
Suresh M