When working with Exchange mailbox automation scripts, we often encounter a common synchronization issue where the mailbox creation hasn't fully completed before subsequent commands execute. Here's a robust solution to handle this scenario:

# Main processing function with retry logic
function Enable-MailboxWithVerification {
    param(
        [string]$DisplayName,
        [string]$DatabaseDN,
        [int]$MaxRetries = 10,
        [int]$RetryDelay = 5
    )
    
    # First enable the mailbox
    Enable-Mailbox -Identity $DisplayName -Database $DatabaseDN
    
    # Verification loop
    $retryCount = 0
    $mailboxReady = $false
    
    while ($retryCount -lt $MaxRetries -and -not $mailboxReady) {
        try {
            $mailbox = Get-Mailbox -Identity $DisplayName -ErrorAction Stop
            if ($mailbox) {
                $mailboxReady = $true
            }
        }
        catch {
            Start-Sleep -Seconds $RetryDelay
            $retryCount++
        }
    }
    
    if (-not $mailboxReady) {
        throw "Mailbox verification timeout for $DisplayName"
    }
    
    return $mailbox
}

Here's how to integrate this into your existing script:

$DName = Read-Host "User Display Name (New User)"
$RUser = Read-Host "Replicate User (Database Grab)"
$RData = ((Get-Mailbox -Identity $RUser).Database).DistinguishedName

# Use our new function instead of direct Enable-Mailbox
$newMailbox = Enable-MailboxWithVerification -DisplayName $DName -Database $RData

# Now safely proceed with CAS settings
Set-CASMailbox -Identity $DName -ActiveSyncEnabled $false 
    -ImapEnabled $false -PopEnabled $false

For enterprise environments, consider these additional improvements:

# Enhanced version with status tracking
function Wait-ForMailboxProvisioning {
    param(
        [string]$Identity,
        [int]$Timeout = 300,
        [int]$Interval = 5
    )
    
    $timer = [Diagnostics.Stopwatch]::StartNew()
    $mailbox = $null
    
    do {
        try {
            $mailbox = Get-Mailbox -Identity $Identity -ErrorAction Stop
            
            # Additional verification for Exchange 2016/2019/O365
            if ($mailbox -and $mailbox.Database) {
                $dbStatus = Get-MailboxDatabaseCopyStatus -Identity $mailbox.Database
                if ($dbStatus.Status -eq 'Mounted') {
                    return $mailbox
                }
            }
        }
        catch [Microsoft.Exchange.Data.DataValidationException] {
            # Specific handling for validation errors
        }
        catch {
            # Generic error handling
        }
        
        if ($timer.Elapsed.TotalSeconds -ge $Timeout) {
            throw "Timeout waiting for mailbox $Identity to provision"
        }
        
        Write-Verbose "Waiting for mailbox provisioning ($($timer.Elapsed.TotalSeconds) seconds elapsed)..."
        Start-Sleep -Seconds $Interval
    } while ($true)
}

For mission-critical automation:

• Implement logging with Start-Transcript
• Add notification for provisioning delays
• Consider parallel processing for bulk operations
• Add AD account status verification pre-check

Here's a complete example with all enhancements:

# Full production example
$DName = Read-Host "User Display Name"
$RUser = Read-Host "Template User"

try {
    $template = Get-Mailbox -Identity $RUser -ErrorAction Stop
    $newMailbox = Enable-MailboxWithVerification -DisplayName $DName -Database $template.Database
    
    # Verify all required properties exist
    if (-not $newMailbox.PrimarySmtpAddress) {
        throw "Mailbox created but SMTP address missing"
    }
    
    Set-CASMailbox -Identity $DName -ActiveSyncEnabled $false
    # Additional configuration commands...
}
catch {
    Write-Error "Failed to process mailbox: $_"
    # Include error notification logic here
}

When automating Exchange mailbox provisioning through PowerShell, we often encounter timing issues where subsequent cmdlets execute before Active Directory replication completes. The core problem manifests when trying to modify CAS settings immediately after mailbox creation.

# Common error pattern
Enable-Mailbox -Identity "NewUser" -Database "DB01"
Set-CASMailbox -Identity "NewUser" -ActiveSyncEnabled $false  # Fails here

Exchange maintains multiple directory components that require synchronization:

• Active Directory domain controller replication
• Exchange attribute propagation
• Mailbox database availability

Here's an enhanced version of your script with multiple wait strategies:

function Wait-ForMailbox {
    param(
        [string]$Identity,
        [int]$Timeout = 120,
        [int]$Interval = 5
    )
    
    $timer = [Diagnostics.Stopwatch]::StartNew()
    do {
        try {
            $null = Get-Mailbox -Identity $Identity -ErrorAction Stop
            return $true
        } catch {
            if ($timer.Elapsed.TotalSeconds -ge $Timeout) {
                throw "Timeout waiting for mailbox '$Identity' to be available"
            }
            Start-Sleep -Seconds $Interval
        }
    } while ($true)
}

# Main script execution
$DName = Read-Host "User Display Name"
$RUser = Read-Host "Template User"
$RData = (Get-Mailbox -Identity $RUser).Database.DistinguishedName

Enable-Mailbox -Identity $DName -Database $RData
Wait-ForMailbox -Identity $DName -Timeout 300

# Now safe to configure CAS settings
Set-CASMailbox -Identity $DName -ActiveSyncEnabled $false -ImapEnabled $false -PopEnabled $false

For enterprise environments, consider these additional safeguards:

try {
    Enable-Mailbox -Identity $DName -Database $RData -ErrorAction Stop
    
    # Exponential backoff wait
    $retryCount = 0
    $maxRetries = 5
    do {
        try {
            $mailbox = Get-Mailbox -Identity $DName -ErrorAction Stop
            break
        } catch {
            $retryCount++
            if ($retryCount -ge $maxRetries) {
                throw
            }
            $sleepTime = [math]::Pow(2, $retryCount)
            Start-Sleep -Seconds $sleepTime
        }
    } while ($true)
    
    # Verify all required properties exist
    if (-not $mailbox.Database) {
        throw "Incomplete mailbox provisioning detected"
    }
} catch {
    Write-Error "Mailbox provisioning failed: $_"
    exit 1
}

When processing bulk operations, implement parallel waiting with throttling:

$maxConcurrent = 5
$mailboxes | ForEach-Object -ThrottleLimit $maxConcurrent -Parallel {
    # Enable each mailbox
    Enable-Mailbox -Identity $_.Identity
    
    # Individual wait process
    while (-not (Get-Mailbox -Identity $_.Identity -ErrorAction SilentlyContinue)) {
        Start-Sleep -Seconds 10
    }
}