Get-SharedMailMembers.ps1

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

<#
    .SYNOPSIS
    Gets and optionally exports members of an Exchange Online distribution list or shared mailbox.

    .DESCRIPTION

    Gets members of an Exchange Online distribution list or shared mailbox, looks up the recipient/delegate details, and presents them to the user for optional export.
    
    Author: James Schlackman <james@schlackman.org>
    Last Modified: Mar 13 2026

    .PARAMETER Identity
    Specifies the distribution group, mail-enabled security group, or shared mailbox.

    .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
    )

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

    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
        }
    }
}