Hi Peter, Yes, there is a way which is not related with PPM application server, it's about oracle application. In Oracle PPM scheme, when a timesheet sent to approver, TM_TIME_SHEET_LINES table STATE field change (I don't know what value). So a triger can dedect change in STATE field change and get ACTUAL_APPROVER_USER_ID field value and send an email to him.
Not easy but will work
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IT Governance Professional & PPM Solution Architect