Anyone have a Powershell script to look up the MX record for a domain?

Question

I want to check to see if the email addresses in my contact management system are valid and the best way I can think to do this is to get the MX record for their domain, then open an SMTP connection and see if the remote server accepts the email address as a valid "TO".

Answer 1

Have a look at the Powershell Dig Cmdlet.

Using this you are able to do this:

PS> $allRecords = Get-Dns -Name mydomain.com -Type MX
PS> write-host $allRecords.RecordsMX

$allRecords is of type PoshNet.Dns.Response so you can read the properties on it to get your records.

Something else nice about this cmdlet is that you can have it return multiple types of records in a single query.

Answer 2

function Get-DnsAddressList
{
    param(
        [parameter(Mandatory=$true)][Alias("Host")]
          [string]$HostName)

    try {
        return [System.Net.Dns]::GetHostEntry($HostName).AddressList
    }
    catch [System.Net.Sockets.SocketException] {
        if ($_.Exception.ErrorCode -ne 11001) {
            throw $_
        }
        return = @()
    }
}

function Get-DnsMXQuery
{
    param(
        [parameter(Mandatory=$true)]
          [string]$DomainName)

    if (-not $Script:global_dnsquery) {
        $Private:SourceCS = @'
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Runtime.InteropServices;

namespace PM.Dns {
  public class MXQuery {
    [DllImport("dnsapi", EntryPoint="DnsQuery_W", CharSet=CharSet.Unicode, SetLastError=true, ExactSpelling=true)]
    private static extern int DnsQuery(
        [MarshalAs(UnmanagedType.VBByRefStr)]
        ref string pszName, 
        ushort     wType, 
        uint       options, 
        IntPtr     aipServers, 
        ref IntPtr ppQueryResults, 
        IntPtr pReserved);

    [DllImport("dnsapi", CharSet=CharSet.Auto, SetLastError=true)]
    private static extern void DnsRecordListFree(IntPtr pRecordList, int FreeType);

    public static string[] Resolve(string domain)
    {
        if (Environment.OSVersion.Platform != PlatformID.Win32NT)
            throw new NotSupportedException();

        List<string> list = new List<string>();

        IntPtr ptr1 = IntPtr.Zero;
        IntPtr ptr2 = IntPtr.Zero;
        int num1 = DnsQuery(ref domain, 15, 0, IntPtr.Zero, ref ptr1, IntPtr.Zero);
        if (num1 != 0)
            throw new Win32Exception(num1);
        try {
            MXRecord recMx;
            for (ptr2 = ptr1; !ptr2.Equals(IntPtr.Zero); ptr2 = recMx.pNext) {
                recMx = (MXRecord)Marshal.PtrToStructure(ptr2, typeof(MXRecord));
                if (recMx.wType == 15)
                    list.Add(Marshal.PtrToStringAuto(recMx.pNameExchange));
            }
        }
        finally {
            DnsRecordListFree(ptr1, 0);
        }

        return list.ToArray();
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct MXRecord
    {
        public IntPtr pNext;
        public string pName;
        public short  wType;
        public short  wDataLength;
        public int    flags;
        public int    dwTtl;
        public int    dwReserved;
        public IntPtr pNameExchange;
        public short  wPreference;
        public short  Pad;
    }
  }
}
'@

        Add-Type -TypeDefinition $Private:SourceCS -ErrorAction Stop
        $Script:global_dnsquery = $true
    }

    [PM.Dns.MXQuery]::Resolve($DomainName) | % {
        $rec = New-Object PSObject
        Add-Member -InputObject $rec -MemberType NoteProperty -Name "Host"        -Value $_
        Add-Member -InputObject $rec -MemberType NoteProperty -Name "AddressList" -Value $(Get-DnsAddressList $_)
        $rec
    }
}

Get-DnsMXQuery -DomainName "gmail.com"

Answer 3

Get-WmiObject -Class MicrosoftDNS_MXType -Namespace root\microsoftdns -ComputerName DC1 -Filter "DomainName='domain.com.'"

Answer 4

On Server 2012/Windows 8 and above you can use Resolve-DnsName:

Resolve-DnsName -Name mydomain.com -Type MX

Source Use PowerShell to Quickly Check Multiple MX Records.