Get-DomainMailSetup.ps1

<#
    .SYNOPSIS
    Retrieves an audit of MX, SPF, and DMARC records from public DNS for a given list of domains.

    .DESCRIPTION
    Author: James Schlackman
    Last Modified: March 20 2025

    .PARAMETER DomainPath
    Pathname to CSV file with list of domains to check.

    .PARAMETER DomainNameField
    Column name in CSV file that identifies the domain names to check.

    .PARAMETER OutputPath
    Export file pathname.
#>

Param(
    [Parameter(Mandatory)] [String]$ImportPath,
    [Parameter()] [String] $DomainNameField,
    [Parameter()] [ValidateNotNullorEmpty()] [String] $OutputPath = ('{0:yyMMdd} Domain Mail DNS Records.csv' -f (Get-Date))
)

# Attempt to load list of domains
If (Test-Path $ImportPath -ErrorAction SilentlyContinue) {
    $domainList = Import-Csv -Path $ImportPath

    # Get list of valid potential domain name fields
    $fields = (@($domainList)[0] | Get-Member -MemberType NoteProperty) | Select Name, @{Name='Sample data';Expression={($_.Definition -split '=')[1]}} | Where-Object {$_.'Sample data'}

    # Select domain name field if not specified
    If (!$DomainNameField) {
        $DomainNameField = ($fields | Out-GridView -Title 'Select import field to identify domain' -OutputMode Single).Name
        Write-Host ('Import file domain name field: {0}' -f $DomainNameField)
    } Else {
        If ($fields.Name -notcontains $DomainNameField) {
            Write-Error 'Specified domain name field not found in import file, or field data empty.'
            Exit
        }
    }
}

# Report number loaded
Write-Host ('Domains to check: {0}' -f $domainList.Count)

# Now check them
If ($domainList) {

    Write-Host 'Retrieving MX, SPF, and DMARC records...'

    $auditOutput = foreach ($domainName in $domainList.$DomainNameField) {

        Write-Debug $domainName

        $soa = Resolve-DnsName -Type SOA -Name $domainName -ErrorAction SilentlyContinue

        If ($soa) {

            [PSCustomObject]@{
                Name = $domainName
                PrimaryServer = $soa.PrimaryServer
                NameAdministrator = $soa.NameAdministrator
                DMARC = (Resolve-DnsName -Type TXT -Name ('_dmarc.{0}' -f $domainName) -ErrorAction SilentlyContinue) | Where-Object {$_.Strings -ne $null} | Select -ExpandProperty Strings
                MX = ((Resolve-DnsName -Type MX -Name $domainName -ErrorAction SilentlyContinue).NameExchange -join ', ')
                SPF = ((Resolve-DnsName -Type TXT -Name $domainName -ErrorAction SilentlyContinue) |
                        Where-Object {$_.Strings -Match 'v=spf1'} |
                        Select -ExpandProperty Strings) -join ''
            } 

        } Else {
            [PSCustomObject]@{
                Name = $domainName
                PrimaryServer = 'Not found'
            }
        }
    }

    Write-Host 'Done.'

    $exportOutput = $auditOutput | Out-GridView -OutputMode Multiple -Title 'Select records for export'

    # If at least 1 record was selected for export
    If ($exportOutput) {
        Write-Host 'Exporting to ' -NoNewline
        Write-Host $OutputPath -ForegroundColor Green
        $exportOutput | Export-Csv -NoTypeInformation -Path ($OutputPath) -Encoding UTF8
    }
}