How to Sync Exchange Online Proxy Addresses with Active Directory

Sync Exchange Online Proxy Addresses with Active Directory

This script connects to Exchange Online, retrieves all mailboxes, and matches each mailbox with a corresponding Active Directory (AD) user based on the primary SMTP address. It then filters out email addresses from a specified excluded domain and formats the remaining proxy addresses. These filtered proxy addresses are then added to the AD user. The script also includes error handling for cases where no or multiple matching AD users are found, and logs any issues with updating the AD user.

---

Script Overview

Ideal for: Exchange administrators managing hybrid email environments

Key Features:

• Mailbox Synchronization - Connects Exchange Online with Active Directory
• Domain Filtering - Excludes specified domains from proxy address sync
• Error Handling - Comprehensive logging for troubleshooting
• Batch Processing - Handles multiple mailboxes efficiently

---

Script Implementation

# Define the Exchange Online organization and excluded domain

$Organization = "xxx.com"
$ExcludeDomain = "xxx.onmicrosoft.com"

# Connect to Exchange Online

Connect-ExchangeOnline -Organization $Organization -ErrorAction Stop

# Get all mailboxes

$AllMailboxs = Get-Mailbox

# Get all Active Directory users

$AllADUsers = Get-ADUser -Filter *

# Loop through each mailbox

foreach ($Mailbox in $AllMailboxs) {
    # Find the corresponding AD user based on the mailbox's primary SMTP address

    $ADUser = $AllADUsers | Where-Object EmailAddress -eq $($Mailbox.PrimarySmtpAddress)

    # Handle different scenarios based on the number of matching AD users

    switch ($ADUser.count) {
        0 { Write-Warning "No AD User found with $($Mailbox.PrimarySmtpAddress) E-mail address" }
        {$_ -gt 1} { Write-Warning "Multiple AD Users found with $($Mailbox.PrimarySmtpAddress) E-mail address" }
        1 {
            # Filter out addresses with excluded domain and correct formatting

            $Addresses = $Mailbox.EmailAddresses | Where-Object {($_ -like "smtp:*") -and ($_ -notlike "*$ExcludeDomain")}

            if ($Addresses) {
                # Correct formatting for proxy addresses

                $Addresses = $Addresses -creplace "SMTP:", "smtp:"

                # Prepare hash to add proxy addresses

                $HashToAdd = @{'proxyAddresses' = $Addresses}

                try {
                    # Update the AD user with new proxy addresses

                    $ADUser | Set-ADUser -Add $HashToAdd -ErrorAction Stop
                    Write-Output "Updated $($Mailbox.EmailAddresses) proxyAddresses successfully"
                }
                catch {
                    Write-Output "Failed to update $($Mailbox.EmailAddresses) proxyAddresses. Error: $($_.Exception.Message)"
                }
            }
        }
    }
}

---

Configuration Requirements

Prerequisites

Component	Requirement	Purpose
Exchange Online Module	ExchangeOnlineManagement	Connect to Exchange Online
Active Directory Module	ActiveDirectory	Manage AD user attributes
Exchange Admin Rights	Mailbox management permissions	Access mailbox data
AD Admin Rights	User attribute modification	Update proxy addresses

Configuration Parameters

Parameter	Example	Description
Organization	"contoso.com"	Exchange Online organization
ExcludeDomain	"contoso.onmicrosoft.com"	Domain to exclude from sync

---

Script Logic Flow

Processing Steps

1. Connect to Exchange Online

   • Establish authenticated connection
   • Retrieve all mailbox data

2. Retrieve Active Directory Users

   • Get all AD users with email attributes
   • Prepare for matching process

3. Mailbox-AD User Matching

   • Match based on primary SMTP address
   • Handle multiple match scenarios

4. Address Filtering and Formatting

   • Exclude specified domains
   • Format proxy addresses correctly

5. Update Active Directory

   • Apply filtered proxy addresses
   • Log success/failure status

---

Error Handling Scenarios

Scenario	Response	Resolution
No AD User Found	Warning logged	Manual user creation required
Multiple AD Users	Warning logged	Review duplicate accounts
Update Failure	Error logged	Check permissions and data

---

Conclusion

Key Takeaway: This script provides automated synchronization between Exchange Online and Active Directory, ensuring consistent email address management while maintaining control over domain inclusion through configurable filtering.