Get-SharedMailMembers.ps1

#Requires -Module @{ModuleName='ExchangeOnlineManagement'; ModuleVersion='1.0.1'}

<#
    .SYNOPSIS
    Gets and optionally exports members of one or more Exchange Online distribution lists or shared mailboxes.

    .DESCRIPTION

    Gets members of specified Exchange Online distribution lists or shared mailboxes, looks up the recipient/delegate details, and presents them to the user for optional export.
    
    Author: James Schlackman <james@schlackman.org>
    Last Modified: Apr 10 2026

    .PARAMETER Identity
    Specifies the distribution groups, mail-enabled security groups, or shared mailboxes.

    .PARAMETER OutputPath
    Path to optional CSV export file.
    
    If not specified, a default name will be generated using the current date and display name of the group/mailbox.

    .EXAMPLE
    Get-SharedMailMembers -Identity marketing@contoso.com -OutputPath 'Marketing Users.csv'

#>
function Get-SharedMailMembers {
    Param(
        [Parameter(Mandatory)] $Identity,
        [Parameter()] [ValidateNotNullOrEmpty()] [String] $OutputPath
    )

    $rcpts = Get-Recipient -Identity $Identity
    $rcpts | Out-Host

    foreach ($rcpt in $rcpts) {
    
        Write-Host ("`nRetrieving members for {0} ({1})" -f $rcpt.DisplayName, $rcpt.PrimarySMTPAddress)
    
        If ($rcpt.RecipientType -in ('MailUniversalDistributionGroup','MailNonUniversalGroup','MailUniversalSecurityGroup')) {

            # Load distribution group members
            $dgMembers = Get-DistributionGroupMember -Identity $Identity

            Write-Host ('Group members: {0}' -f @($dgMembers).Count)

            $resultList = $dgMembers | Sort-Object -Property PrimarySmtpAddress | Select DisplayName, PrimarySmtpAddress, RecipientTypeDetails, DistinguishedName
    
        } ElseIf ($rcpt.RecipientType -eq 'UserMailbox') {

            # Load shared mailbox delegates
            $mbPerms = (Get-MailboxPermission -Identity $rcpt).User | Where-Object {$_ -notlike '*\*'} | Sort-Object -Unique

            Write-Host ('Shared mailbox delegates: {0}' -f @($mbPerms).Count)

            $resultList = foreach($perm in $mbPerms) {
            
                Get-EXORecipient -Identity $perm | Select DisplayName, PrimarySmtpAddress, RecipientTypeDetails, DistinguishedName 

            }

        }

        If ($resultList) {

            # Set default output path if not specified
            If (!($OutputPath)) {
                $OutputPath = '{0} {1} Members.csv' -f (Get-Date).ToString('yyMMdd'), $rcpt.DisplayName
            }

            # Show in grid
            Write-Host 'See grid export for details and select records for export.'
            $resultExport = $resultList | Out-GridView -OutputMode Multiple -Title 'Select records for export to CSV'

            # Export selected records to file
            If ($resultExport) {
                Write-Host 'Exporting to ' -NoNewline
                Write-Host $OutputPath -ForegroundColor Green
                $resultExport | Export-Csv -NoTypeInformation -Path $OutputPath -Encoding UTF8bom
            }
        }
    }
}