Get-MailboxStatistics | Sort-Object TotalItemSize -Descending | ft DisplayName,@{label="TotalItemSize(KB)";expression={$_.TotalItemSize.Value.ToKB()}},ItemCount
2.Delete disconnected mailbox Exchange
Get-MailboxStatistics | where-object { $_.DisconnectDate -ne $null } | Select DisplayName,MailboxGuid
Insert database name and user’s guid into the following command line and press enter
Remove-Mailbox -Database
