Identifying inactive distribution lists using PowerShell and message trace data

Administrators can identify inactive distribution lists in Exchange Online by analyzing message trace data to see if expansion events have occurred. While the Get-MessageTraceV2 cmdlet is limited to a ten-day window for "warm" data, it can actually retrieve information up to 90 days in the past. To leverage this, a script must divide the 90-day period into nine distinct ten-day chunks and fetch the data for each segment. Source

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