SharePoint External-Sharing Settings

<#
.SYNOPSIS
    Exports each SharePoint Online site's external-sharing setting, last-modified date
    and storage usage to a CSV.
.DESCRIPTION
    Prompts for a tenant ID, connects to the SharePoint admin centre, and reports the
    external-sharing capability (in human-readable form) plus storage for every site.
    Requires the Microsoft.Online.SharePoint.PowerShell module and SPO admin rights.
#>

Import-Module -Name Microsoft.Online.SharePoint.PowerShell -UseWindowsPowerShell

# Tenant ID = the part before .onmicrosoft.com (e.g. 'contoso' for contoso.onmicrosoft.com)
$clientid = Read-Host "Enter the tenant ID (the part before .onmicrosoft.com), e.g. 'contoso' or 'fabrikam'"

$AdminSiteURL= "https://$clientid-admin.sharepoint.com"

Connect-SPOService -url $AdminSiteURL -ModernAuth $true

$filename = "External Sharing Policies.csv"

$downloads = [Environment]::GetFolderPath("UserProfile") + "\Downloads\" + $filename

$sites = Get-SPOSite -Limit All | Select-Object LastContentModifiedDate, Title, SharingCapability, StorageUsageCurrent

$output = $sites | ForEach-Object {
    $humanReadableCapability = switch ($_.SharingCapability) {
        "ExternalUserSharingOnly" { "New and existing guests" }
        "ExistingExternalUserSharingOnly" { "Existing guests only" }
        "Disabled" { "Only people in your organization" }
        "ExternalUserAndGuestSharing" { "Anyone" }
        default { $_.SharingCapability }
    }

    if ($_.StorageUsageCurrent -ge 1024) {
        $size = [math]::Round($_.StorageUsageCurrent / 1024, 2)
        $humanReadableSize = "${size} GB"
    } else {
        $humanReadableSize = "$($_.StorageUsageCurrent) MB"
    }

    $dateOnly = $_.LastContentModifiedDate.ToShortDateString()

    [PSCustomObject]@{
        "LastContentModifiedDate" = $dateOnly
        "Title"                   = $_.Title
        "SharingCapability"       = $humanReadableCapability
        "StorageUsageCurrent"     = $humanReadableSize
    }
}

$output | Export-Csv -Path $downloads -NoTypeInformation

Write-Host -ForeGround Green "The report is complete. $filename has been saved to $downloads."