Import-ExchangeStructure.ps1

[CmdletBinding()]
param(
    [ValidateScript({Test-Path $_ -PathType Leaf})]
    [Parameter(Mandatory=$True,Position=1)][string]$XMLFile
)

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

$logfile = ".\ImportExchangeStructure.log"
$domain = Get-ADDomain
$addomain = $domain.Forest
$domaindn = $domain.DistinguishedName
$ou = "$addomain/Exchange/Distribution Lists"

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
}

function MBinDG([string]$lookinDG, [string]$findname) {
    Set-Variable -Name userexists -Value $false -Scope 0
    $userMB = Get-Mailbox $findname -ErrorAction SilentlyContinue -WarningAction SilentlyContinue
    $lookinDGmbrs = Get-DistributionGroupMember -Identity $lookinDG -ErrorAction SilentlyContinue -WarningAction SilentlyContinue
    $lookinDGmbrs | ForEach-Object {
        if($_.Name -eq $userMB.Name) { $userexists = $true }
    }
    return $userexists
}

$addomain = [System.DirectoryServices.ActiveDirectory.Domain]::GetCurrentDomain().Name
$me = [Environment]::UserName
$nl = "`r`n"

[xml]$dglist = Get-Content $XMLFile
ForEach($dg in $dglist.DistributionGroups.DistributionGroup) {
    $DisplayName = $dg.DisplayName.Replace("OLDDOMAIN","NEWDOMAIN")
    $Name = $dg.Name.Replace("OLDDOMAIN","NEWDOMAIN")
    $Alias = $dg.Alias.Replace("OLDDOMAIN","NEWDOMAIN")
    $ManagedBy = $dg.ManagedBy
    $ModeratedBy = $dg.ModeratedBy
    $Members = $dg.Members
    $testdg = Get-DistributionGroup $Alias -ErrorAction SilentlyContinue

    Write-Host "Name: $Name"
    Write-Host "Alias: $Alias"

    [String[]]$MemberList = ForEach($m in $Members.ReducedRecipient) {
        Set-Variable -Name testmb -Value $null -Scope 0
        Set-Variable -Name testdgm -Value $null -Scope 0
        $mbr = $m.PrimarySmtpAddress
        if($mbr -ne "" -and $mbr -ne $null) {
            $mbr = $mbr.Replace("OLDDOMAIN","NEWDOMAIN")
            if($mbr.Contains("contoso") -or $mbr.Contains("microsoft")) {
                $testmb = Get-Mailbox $mbr -ResultSize 1 -ErrorAction SilentlyContinue -WarningAction SilentlyContinue
                $testdgm = Get-DistributionGroup $mbr -ResultSize 1 -ErrorAction SilentlyContinue -WarningAction SilentlyContinue
                if($testmb -ne $null -or $testdgm -ne $null) {
                    $mbr
                }
                else {
                    writelog "ERROR: Could find mailbox or distribution group $mbr"
                }
            }
        }
    }
    [String[]]$ManagedByList = ForEach($m in $ManagedBy.ADMultiValuedProperty.ADObjectId) {
        Set-Variable -Name testmb -Value $null -Scope 0
        $mbr = $m.PrimarySmtpAddress
        if($mbr -ne "" -and $mbr -ne $null) {
            $mbr = $mbr.Replace("OLDDOMAIN","NEWDOMAIN")
            $testmb = Get-Mailbox $mbr -ResultSize 1 -ErrorAction SilentlyContinue -WarningAction SilentlyContinue
            if($testmb -ne $null) {
                $mbr
            }
        }
    }
    [String[]]$ModeratedByList = ForEach($m in $ModeratedBy.ADMultiValuedProperty.ADObjectId) {
        Set-Variable -Name testmb -Value $null -Scope 0
        $mbr = $m.PrimarySmtpAddress
        if($mbr -ne "" -and $mbr -ne $null) {
            $mbr = $mbr.Replace("OLDDOMAIN","NEWDOMAIN")
            $testmb = Get-Mailbox $mbr -ResultSize 1 -ErrorAction SilentlyContinue -WarningAction SilentlyContinue
            if($testmb -ne $null) {
                $mbr
            }
        }
    }

    $mc = $MemberList.Count
    if($ManagedByList -eq $null) {
        [String[]]$ManagedByList = @($me)
    }
    Write-Host "Members ($mc members): $MemberList"
    Write-Host "Managed By: $ManagedByList"
    Write-Host "Moderated By: $ModeratedByList"

    If($testdg -eq $null) {
        writelog "Creating Distribution Group $DisplayName"
        New-DistributionGroup $Name -Alias $Alias -DisplayName $DisplayName -ManagedBy $ManagedByList `
        -ModeratedBy $ModeratedByList -Members $MemberList -Type Distribution -OrganizationalUnit $ou
    }
    else {
        ForEach($mdn in $MemberList) { if($mdn -ne $null) {
            if($mdn.Trim() -ne "") {
                $useralreadyexists = MBinDG $Alias $mdn
                if($useralreadyexists -eq $false) {
                    writelog "Adding $mdn to $DisplayName"
                    Add-DistributionGroupMember $Name -Member $mdn -BypassSecurityGroupManagerCheck -ErrorAction SilentlyContinue
                }
            }
        } }
    }
    Write-Host $nl
}
$dglist = $null
[gc]::collect()