Nope, but I can think of a solution. Using powershell, use the export API daily to refresh your export of messages. Then write a script.... Import-csv, then foreach-object.... if date > 360, then use the message delete api. Do the first time for all time messages... then change the export to increment after that one time. There's a caveat to that though - The parent message will always be the oldest and replies inside that may reflect newer dates. You can't delete a parent message without deleting every response.