If it is a new App then the Managed application is recommended without CUD.You can create an action and create RFC wrapper FM to put code for sending email and PO update FM like BAPI. You can use COMMIT WORK inside that.Call the FM with DESTINATION '...

Please refer below for the steps to be followed.https://community.sap.com/t5/technology-blogs-by-members/fiori-tile-creation-for-custom-transaction-codes-reports/ba-p/13558745You can refer this.