Create-Mailboxes.ps1

[CmdletBinding()]
param(
    [Parameter(Mandatory=$True,Position=0)][string]$RootOU
)

Import-Module ActiveDirectory
if(!(Get-PSSnapin |
    Where-Object {$_.name -eq "Microsoft.Exchange.Management.PowerShell.E2010"})) {
      ADD-PSSnapin Microsoft.Exchange.Management.PowerShell.E2010
}

$start = Get-Date
$domain = Get-ADDomain
$addomain = $domain.Forest
$domaindn = $domain.DistinguishedName
$logfile = ".\CreateMailboxes.log"
$nl = "`r`n"
$ou = "OU=Users,OU=$RootOU,$domaindn"

function writelog([string]$message) {
    $timestamp = Get-Date
    $fc = "White"
    if($message.contains("ERROR")) {$fc ="Red"}
    Add-content $logfile -value "$timestamp : $message"
    Write-Host $message -ForegroundColor $fc
}

writelog "Creating mailboxes in $ou at $start"
Write-Host $nl

Get-ADUser -SearchBase $ou -LDAPfilter "(objectClass=user)" -properties DisplayName,SamAccountName,EmailAddress | ForEach-Object {
    Set-Variable -Name testmb -Value $null -Scope 0
    $username = $_.SamAccountName
    $upn = $username + "@" + $addomain
    $DisplayName = $_.DisplayName.Trim()
    $DisplayName = $DisplayName.Replace("Contoso","Microsoft")
    $testmb = Get-Mailbox $username -ErrorAction SilentlyContinue
    if($testmb -eq $null) {
        writelog "Creating mailbox $DisplayName"
        Enable-Mailbox $username -DisplayName $DisplayName -Alias $username
    }
    else {
        #writelog "Mailbox  $name already exists, skipping."
    }
}

$end = Get-Date
$elapsed = $end - $start
Write-Host $nl
writelog "Finished import at $end ($elapsed)"