Export-DistributionGroupMembership

<#
.SYNOPSIS
    Exports all distribution groups and their members to CSV.

.DESCRIPTION
    Enumerates every distribution group in the tenant, resolves membership
    for each one, and writes a flat CSV with one row per group/member pair
    so the whole tenant's distribution list membership can be reviewed in
    a spreadsheet instead of one group at a time in the admin center.

.PARAMETER ExportPath
    Path to write the CSV to. Defaults to the current directory.

.EXAMPLE
    .\Export-DistributionGroupMembership.ps1 -ExportPath C:\Reports

.NOTES
    Requires ExchangeOnlineManagement and an active Connect-ExchangeOnline session.

.AUTHOR
    Shehryar Hassan
#>

param(
    [string]$ExportPath = (Get-Location).Path
)

$groups = Get-DistributionGroup -ResultSize Unlimited
$rows = foreach ($group in $groups) {
    $members = Get-DistributionGroupMember -Identity $group.Identity -ResultSize Unlimited
    if ($members) {
        foreach ($member in $members) {
            [pscustomobject]@{
                GroupName    = $group.DisplayName
                GroupEmail   = $group.PrimarySmtpAddress
                MemberName   = $member.DisplayName
                MemberEmail  = $member.PrimarySmtpAddress
            }
        }
    } else {
        [pscustomobject]@{
            GroupName   = $group.DisplayName
            GroupEmail  = $group.PrimarySmtpAddress
            MemberName  = "(empty group)"
            MemberEmail = ""
        }
    }
}

$file = Join-Path $ExportPath "distribution-group-membership_$(Get-Date -Format yyyyMMdd_HHmmss).csv"
$rows | Export-Csv -Path $file -NoTypeInformation
Write-Host "Exported $($rows.Count) rows across $($groups.Count) groups to $file" -ForegroundColor Cyan