How to Automate Welcome Emails for New Exchange On-Premises Users

In a busy IT environment, manual onboarding is a time-consuming process that is prone to human error. While cloud-based suites often provide built-in greeting features, Exchange On-Premises lacks a native ‘Auto-Welcome’ toggle for new mailboxes. To bridge this gap, the most robust and scalable solution is a customized PowerShell automation. In this post, I’ll show you how to build a script that identifies new users and delivers a professional, branded welcome experience automatically.

1. The Strategy: Differential Tracking

Because the goal is to target only new users, the script must distinguish between a fresh mailbox and an established account. We achieve this by querying the WhenMailboxCreated metadata. By applying a time-relative filter, the script can isolate accounts created within a specific window (e.g., the last 60 minutes or 24 hours), ensuring that long-term employees don’t receive redundant onboarding mail.

The Logic Flow

Step 1: Scan & Identify – The script queries the Exchange environment to find mailboxes where the WhenMailboxCreated timestamp is greater than the defined $TimeLimit.

Step 2: Filter & Validate – To avoid “Welcome” emails being sent to service accounts or discovery mailboxes, we filter the results. Additionally, we check a Custom Attribute (e.g., CustomAttribute1) to verify if a welcome email has already been sent, providing a “failsafe” against duplicates.

Step 3: Execution – For every valid new user identified, the script generates a stylized HTML body, pulls the organization name from the Company attribute, and dispatches the email via SMTP relay.

Step 4: Persistence – After a successful send, the script updates the user’s mailbox attribute to “WelcomeSent,” effectively marking the task as complete for that specific identity.

Step 5: Automation – Finally, we utilize Windows Task Scheduler to trigger the script at regular intervals, creating a fully autonomous onboarding loop.

2. The PowerShell Script

You can run this on your Exchange Management Shell.

<#
.SYNOPSIS
    Exchange On-Premise New User Welcome Mailer
.DESCRIPTION
    Scans for new mailboxes created in the last 60 minutes and sends a 
    branded HTML welcome email with an attachment.
.AUTHOR
    MAHARJAN-BINOD
#>

# --- 1. PRE-REQUISITES ---
if (!(Get-PSSnapin Microsoft.Exchange.Management.PowerShell.E2010 -ErrorAction SilentlyContinue)) {
    Add-PSSnapin Microsoft.Exchange.Management.PowerShell.E2010
}

# --- 2. CONFIGURATION ---
$MinutesBack = 60 
$TimeLimit = (Get-Date).AddMinutes(-$MinutesBack)
$SMTPServer = "127.0.0.1" 
$From = "HR-Onboarding@maharjan.com.np"
$AdminCC = "exgadmin@maharjan.com.np"
$ManagerBCC = "audit-logs@maharjan.com.np"
$AttachmentPath = "C:\Reports\Combined_MailboxLoginReport.html"

# --- 3. EXECUTION ---
Write-Host "Scanning for new mailboxes since $TimeLimit..." -ForegroundColor Cyan

$NewMailboxes = Get-Mailbox -ResultSize Unlimited | Where-Object { 
    $_.WhenMailboxCreated -gt $TimeLimit -and $_.CustomAttribute1 -ne "WelcomeSent" 
}

if ($NewMailboxes -ne $null) {
    foreach ($User in $NewMailboxes) {
        $OrgName = $User.Company
        if ([string]::IsNullOrWhiteSpace($OrgName)) { $OrgName = "MAHARJAN-BINOD" }

        $To = $User.PrimarySmtpAddress
        $DisplayName = $User.DisplayName
        $Subject = "Welcome to $OrgName - New Account Created"

        $Body = @"
        <!-- Beautiful HTML Email Template Logic Starts Here -->
        <div class='header'>Welcome to the Team, $DisplayName!</div>
        <!-- [Template Code Included in actual script] -->
"@

        try {
            $Params = @{
                SmtpServer = $SMTPServer
                Port       = 25
                From       = $From
                To         = $To
                Cc         = $AdminCC
                Bcc        = $ManagerBCC
                Subject    = $Subject
                Body       = $Body
                BodyAsHtml = $true
                Priority   = "High"
                ErrorAction = "Stop"
            }

            if (Test-Path $AttachmentPath) {
                $Params.Add("Attachments", $AttachmentPath)
            }

            Send-MailMessage @Params
            Set-Mailbox -Identity $User.DistinguishedName -CustomAttribute1 "WelcomeSent"
            
            Write-Host "SUCCESS: Welcome mail sent to $To" -ForegroundColor Green
        }
        catch {
            Write-Warning "Failed to send to $To."
        }
    }
}

3. Implementation Steps

B. Preventing Duplicate Notifications (The “Safety Switch”)

C. Continuous Automation via Task Scheduler

4. Key Implementation Considerations

1. SMTP Relay Permissions

For the Send-MailMessage command to function, the server executing the script must be authorized to relay mail. You must configure your Exchange Receive Connector to allow anonymous or authenticated relaying from the script’s source IP address. If you are running the script locally on the Exchange server using 127.0.0.1, ensure the “Default Frontend” connector is set up to accept the traffic.

2. Managing the Initial Run (Avoid “The Blast”)

When you execute the script for the first time, be extremely careful with your $TimeLimit. If it is set to 24 hours, the script will attempt to email every user created in the last day who hasn’t been “stamped” yet.

• Pro-Tip: For the very first run, you may want to manually “stamp” existing users’ CustomAttribute1 to WelcomeSent or temporarily set the $MinutesBack to a very small number (e.g., 5 minutes) to test the logic on a single fresh account.

3. Attachment Handling

If you are including a corporate policy or “Org Guide” PDF, ensure the file path is accessible to the account running the scheduled task. You can dynamically attach files using the -Attachments parameter: Send-MailMessage @Params -Attachments "C:\Docs\Rules.pdf"

• Best Practice: Always use the Test-Path command within your script to verify the file exists before attempting to send the email; this prevents the script from crashing if the document is moved or renamed.

4. Security & Privacy

Since this script handles employee data and dispatches emails to the entire organization, ensure that the folder containing your .ps1 file has restricted NTFS permissions. Only authorized administrators and the System/Service account running the Task Scheduler should have “Read” and “Execute” access.

5. The Result: A Professional Welcome Experience

Once the Task Scheduler triggers the script and a new mailbox is detected, the magic happens. The user doesn’t receive a dry, system-generated notification; instead, they are greeted with a branded, modern email that sets the tone for their journey with the company.

Re-run for script again.

In End user login:

Magic happens!

Done.

Conclusion

Automating the “Welcome” email for new mailboxes is more than just a convenience—it’s about creating a professional first impression for your new team members. By leveraging PowerShell and the Windows Task Scheduler, we’ve turned a manual administrative burden into a reliable, “set-it-and-forget-it” system.

This workflow ensures that every user, from their first hour on the job, has the tools and guidelines they need to succeed, while IT stays focused on higher-priority tasks.

Happy Scripting!

Troubleshooting: Common Pitfalls

Even with a perfect script, Exchange environments can be finicky. Here are the most common issues you might encounter:

• The 4.7.0 PRX2 Error: This is a common error when running scripts locally on an Exchange server. It usually indicates a DNS or load-balancing issue within the Frontend/Backend connectors.
  • Solution: Ensure your $SMTPServer is set to 127.0.0.1. This forces the script to talk directly to the local relay rather than jumping through external DNS loops.
• Execution Policy Block: If your task fails to start, PowerShell might be blocking the script due to security policies.
  • Solution: Always use the -ExecutionPolicy Bypass flag in your Task Scheduler arguments to allow the script to run without manual intervention.
• Module Not Found: If you see an error stating Get-Mailbox is not recognized, the Exchange Snapin failed to load.
  • Solution: Verify that the script is running on a machine with the Exchange Management Tools installed and that the Add-PSSnapin command at the top of the script points to the correct version (e.g., E2010 vs. E2013+).
• Permissions (Access Denied): The script might fail to update CustomAttribute1.
  • Solution: Ensure the service account running the Task Scheduler is a member of the Recipient Management or Organization Management role groups in Exchange.