Find DLs with External Users

Find DLs with External Users/DLsWithExternalUsers.ps1

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+<#
+=============================================================================================
+Name:           Get Distribution Lists with External Users in Microsoft 365  
+Version:        1.0
+Website:        o365reports.com
+
+
+Script Highlights:  
+~~~~~~~~~~~~~~~~~
+1. Generates a list of distribution groups with external users in Microsoft 365.  
+2. Excludes external mail contacts by default, with an option to include them if required. 
+3. The script automatically verifies and installs the Exchange PowerShell module (if not installed already) upon your confirmation. 
+4. Exports report results to CSV. 
+5. The script supports Certificate-based authentication (CBA).  
+6. The script is schedular friendly.  
+
+For detailed Script execution: https://o365reports.com/2024/12/17/get-distribution-lists-with-external-users-in-microsoft-365/
+
+
+============================================================================================
+#>Param
+(
+    [Parameter(Mandatory = $false)]
+	[string]$UserName=$Null,
+    [string]$Password=$Null,
+    [string]$Organization,
+    [string]$ClientId,
+    [string]$CertificateThumbprint,
+	[switch]$IncludeContacts
+	)
+Function Connect_Exo
+{
+ #Check for EXO module inatallation
+ $Module = Get-Module ExchangeOnlineManagement -ListAvailable
+ if($Module.count -eq 0) 
+ { 
+  Write-Host Exchange Online PowerShell  module is not available  -ForegroundColor yellow  
+  $Confirm= Read-Host Are you sure you want to install module? [Y] Yes [N] No 
+  if($Confirm -match "[yY]") 
+  { 
+   Write-host "Installing Exchange Online PowerShell module"
+   Install-Module ExchangeOnlineManagement -Repository PSGallery -AllowClobber -Force
+  } 
+  else 
+  { 
+   Write-Host EXO module is required to connect Exchange Online.Please install module using Install-Module ExchangeOnlineManagement cmdlet. 
+   Exit
+  }
+ } 
+ Write-Host Connecting to Exchange Online...
+ #Storing credential in script for scheduling purpose/ Passing credential as parameter - Authentication using non-MFA account
+ if(($UserName -ne "") -and ($Password -ne ""))
+ {
+  $SecuredPassword = ConvertTo-SecureString -AsPlainText $Password -Force
+  $Credential  = New-Object System.Management.Automation.PSCredential $UserName,$SecuredPassword
+  Connect-ExchangeOnline -Credential $Credential -ShowBanner:$false
+ }
+ elseif($Organization -ne "" -and $ClientId -ne "" -and $CertificateThumbprint -ne "")
+ {
+   Connect-ExchangeOnline -AppId $ClientId -CertificateThumbprint $CertificateThumbprint  -Organization $Organization -ShowBanner:$false
+ }
+ else
+ {
+  Connect-ExchangeOnline -ShowBanner:$false
+ }
+}
+
+Connect_Exo
+$Location=Get-Location
+$OutputCsv="$Location\DLs_with_ExternalUsers_Report_$((Get-Date -format yyyy-MMM-dd-ddd` hh-mm` tt).ToString()).csv"
+$DLWithExternalUsersCount=0
+$DLCount=0
+    
+#Processing all DLs
+Get-DistributionGroup -ResultSize Unlimited | ForEach{
+ $DLCount++
+ Write-Progress -Activity "Finding Distribution List with ExternalUsers:" -Status "Processed DL Count: $DLCount" -CurrentOperation "Currently Processing DL Name: $_ "
+ $DLName =$_.Name
+ $DLEmailAddress=$_.PrimarySMTPAddress
+ If($IncludeContacts.IsPresent)
+ {
+  $ExternalUsers=(Get-DistributionGroupMember $_.Name  |where{$_.RecipientType -eq "MailContact" -or $_.RecipientType -eq "MailUser" })
+ }
+ Else
+ {
+  $ExternalUsers=(Get-DistributionGroupMember $_.Name  |where{ $_.RecipientType -eq "MailUser" })	
+ }
+
+ #Processing DLs with external users
+ $ExternalUsersCount= ($ExternalUsers | Measure-Object).count
+ If($ExternalUsersCount -ne '0')
+ {
+  $EmailAddress=$ExternalUsers.ExternalEmailAddress | foreach {
+    $_.split(":")[1]}
+  $EmailAddress= $EmailAddress -join (",")
+  $ExternalUserName=$ExternalUsers.Name -join ','
+  $ExternalUserDisplayName=$ExternalUsers.DisplayName -join ','
+  $Result=New-Object PsObject -Property @{'DL Name'=$DLName;'DL Email Address'=$DLEmailAddress;'No of External Users in DL'=$ExternalUsersCount;'External Users Name'=$ExternalUserName;'External Users Display Name'=$ExternalUserDisplayName;'Exterenal Users Email Address'=$EmailAddress}
+  $Result|Select-Object 'DL Name','DL Email Address','No of External Users in DL','External Users Name','External Users Display Name','Exterenal Users Email Address'|Export-CSV -Path $OutputCsv -NoTypeInformation -Append
+  $DLWithExternalUsersCount++
+ }
+}
+
+#Disconnect Exchange Online session
+Disconnect-ExchangeOnline -Confirm:$false
+
+
+Write-Host `n~~ Script prepared by AdminDroid Community ~~`n -ForegroundColor Green
+Write-Host "~~ Check out " -NoNewline -ForegroundColor Green; Write-Host "admindroid.com" -ForegroundColor Yellow -NoNewline; Write-Host " to get access to 1800+ Microsoft 365 reports. ~~" -ForegroundColor Green `n
+ 
+
+if((Test-Path -Path $OutputCsv) -eq "True") 
+{
+ Write-Host $DLWithExternalUsersCount DLs contain external user as members.
+ Write-Host `nDetailed report available in: -NoNewline -Foregroundcolor Yellow; Write-Host $OutputCSV
+ $Prompt = New-Object -ComObject wscript.shell   
+  $UserInput = $Prompt.popup("Do you want to open output file?",`   
+ 0,"Open Output File",4)   
+ If ($UserInput -eq 6)   
+ {   
+   Invoke-Item "$OutputCSV"   
+ } 
+}
+else
+{
+ Write-Host No DLs found with the specific criteria.
+}