微软官方提供了一个文档和PowerShell进行相关的操作。
https://docs.microsoft.com/en-us/office365/troubleshoot/audit-logs/mailbox-audit-logs

param ([PARAMETER(Mandatory=$TRUE,ValueFromPipeline=$FALSE)]
[string]$Mailbox,
[PARAMETER(Mandatory=$TRUE,ValueFromPipeline=$FALSE)]
[string]$StartDate,
[PARAMETER(Mandatory=$TRUE,ValueFromPipeline=$FALSE)]
[string]$EndDate,
[PARAMETER(Mandatory=$FALSE,ValueFromPipeline=$FALSE)]
[string]$Subject,
[PARAMETER(Mandatory=$False,ValueFromPipeline=$FALSE)]
[switch]$IncludeFolderBind,
[PARAMETER(Mandatory=$False,ValueFromPipeline=$FALSE)]
[switch]$ReturnObject)
BEGIN {
  [string[]]$LogParameters = @(‘Operation‘, ‘LogonUserDisplayName‘, ‘LastAccessed‘, ‘DestFolderPathName‘, ‘FolderPathName‘, ‘ClientInfoString‘, ‘ClientIPAddress‘, ‘ClientMachineName‘, ‘ClientProcessName‘, ‘ClientVersion‘, ‘LogonType‘, ‘MailboxResolvedOwnerName‘, ‘OperationResult‘)
  }
  END {
    if ($ReturnObject)
    {return $SearchResults}
    elseif ($SearchResults.count -gt 0)
    {
    $Date = get-date -Format yyMMdd_HHmmss
    $OutFileName = "AuditLogResults$Date.csv"
    write-host
    write-host -fore green ‘Posting results to file: $OutfileName‘
    $SearchResults | export-csv $OutFileName -notypeinformation -encoding UTF8
    }
    }
    PROCESS
    {
    write-host -fore green ‘Searching Mailbox Audit Logs...‘
    $SearchResults = @(search-mailboxAuditLog $Mailbox -StartDate $StartDate -EndDate $EndDate -LogonTypes Owner, Admin, Delegate -ShowDetails -resultsize 50000)
    write-host -fore green ‘$($SearchREsults.Count) Total entries Found‘
    if (-not $IncludeFolderBind)
    {
    write-host -fore green ‘Removing FolderBind operations.‘
    $SearchResults = @($SearchResults | ? {$_.Operation -notlike ‘FolderBind‘})
    write-host -fore green ‘Filtered to $($SearchREsults.Count) Entries‘
    }
    $SearchResults = @($SearchResults | select ($LogParameters + @{Name=‘Subject‘;e={if (($_.SourceItems.Count -eq 0) -or ($_.SourceItems.Count -eq $null)){$_.ItemSubject} else {($_.SourceItems[0].SourceItemSubject).TrimStart(‘ ‘)}}},
    @{Name=‘CrossMailboxOp‘;e={if (@(‘SendAs‘,‘Create‘,‘Update‘) -contains $_.Operation) {‘N/A‘} else {$_.CrossMailboxOperation}}}))
    $LogParameters = @(‘Subject‘) + $LogParameters + @(‘CrossMailboxOp‘)
    If ($Subject -ne ‘‘ -and $Subject -ne $null)
    {
    write-host -fore green ‘Searching for Subject: $Subject‘
    $SearchResults = @($SearchResults | ? {$_.Subject -match $Subject -or $_.Subject -eq $Subject})
    write-host -fore green ‘Filtered to $($SearchREsults.Count) Entries‘
    }
    $SearchResults = @($SearchResults | select $LogParameters)
    }

执行之后 会自动生成对应的Excel文档, 谁在什么时候，从什么客户端的IP，做了什么操作一目了然

PowerShell 审计Office365 邮箱操作日志