For AD SMTP and Alias’

<#
.SYNOPSIS
    Export SMTP addresses (primary + secondary) from AD users.

.DESCRIPTION
    Uses Get-ADUser to collect the 'proxyAddresses' and 'mail' attributes.
    - Primary SMTP is the address with the "SMTP:" prefix (uppercase).
    - Other SMTP addresses are those with the "smtp:" prefix (lowercase).
    - If proxyAddresses is empty, the script will attempt to use the 'mail' attribute as primary.

.PARAMETER OutputCsv
    File path for exported CSV. Default: .\AD-SMTP-Addresses.csv

.PARAMETER SearchBase
    Optional AD container (distinguishedName) to restrict the search.

.PARAMETER IncludeDisabled
    If specified, include disabled accounts as well. By default disabled accounts are excluded.

.EXAMPLE
    .\Export-AD-SMTP.ps1 -OutputCsv C:\temp\smtp-addresses.csv

#>

param(
    [string]$OutputCsv = ".\AD-SMTP-Addresses.csv",
    [string]$SearchBase,
    [switch]$IncludeDisabled
)

# Ensure ActiveDirectory module is available
if (-not (Get-Module -ListAvailable -Name ActiveDirectory)) {
    Write-Error "The ActiveDirectory module is not installed or available. Install RSAT/Active Directory module and run again."
    exit 1
}

Import-Module ActiveDirectory -ErrorAction Stop

# Build filter
$filter = if ($IncludeDisabled) { { } } else { { Enabled -eq $true } }

# Properties we need
$properties = @("proxyAddresses","mail","distinguishedName","samAccountName","displayName","objectClass")

try {
    if ($SearchBase) {
        $users = Get-ADUser -Filter * -SearchBase $SearchBase -Properties $properties
    } else {
        $users = Get-ADUser -Filter * -Properties $properties
    }
}
catch {
    Write-Error "Failed to query Active Directory: $_"
    exit 1
}

$result = foreach ($u in $users) {
    # Some objects may not have proxyAddresses (or not be users) - handle safely
    $proxy = @()
    if ($u.proxyAddresses) {
        $proxy = $u.proxyAddresses
    }

    # Normalize and split SMTP addresses
    $primary = $null
    $others  = @()

    if ($proxy.Count -gt 0) {
        # find exact uppercase SMTP: for primary
        $primaryEntry = $proxy | Where-Object { $_ -like "SMTP:*" } | Select-Object -First 1
        if ($primaryEntry) {
            $primary = $primaryEntry -replace '^[sS][mM][tT][pP]:',''  # remove prefix (case-insensitive)
        } else {
            # no uppercase SMTP found -> try any smtp: entry as fallback
            $fallback = $proxy | Where-Object { $_ -match '^(smtp|SMTP):' } | Select-Object -First 1
            if ($fallback) { $primary = $fallback -replace '^[sS][mM][tT][pP]:','' }
        }

        $others = $proxy |
            Where-Object { $_ -match '^(smtp|SMTP):' } |
            Where-Object { ($_ -replace '^[sS][mM][tT][pP]:','') -ne $primary } |
            ForEach-Object { $_ -replace '^[sS][mM][tT][pP]:','' }
    }

    # If no proxyAddresses, fall back to mail attribute as primary (if present)
    if (-not $primary -and $u.mail) {
        $primary = $u.mail
    }

    # Build object for export
    [PSCustomObject]@{
        DistinguishedName = $u.DistinguishedName
        SamAccountName    = $u.SamAccountName
        DisplayName       = $u.DisplayName
        ObjectClass       = $u.ObjectClass
        PrimarySMTP       = $primary
        OtherSMTPs        = if ($others.Count -gt 0) { $others -join ";" } else { $null }
    }
}

# Export to CSV
try {
    $result | Export-Csv -Path $OutputCsv -NoTypeInformation -Encoding UTF8
    Write-Output "Export completed: $OutputCsv ('$($result.Count) records)'"
}
catch {
    Write-Error "Failed to export CSV: $($_)"
    exit 1
}