Powershell Script to Get Report on 420 4.2.0 RESOLVER.ADR.Ambiguous in Message queue on Exchange Server

There are certain situation  due to witch multiple recipients could be found with the same SMTP addresses, which leads Messages for that SMTP address to stuck in the mail queue with Error "420 4.2.0 RESOLVER.ADR.Ambiguous", It is important to fix this situation before users start complaining that they are not getting emails or missing some.

Below Powershell Scripts is handy for monitoring mail queue for message stuck with ambiguous Address status, and will get you snap shot of mail queue with Ambiguous Status in html format, and also fetches the further details on the recipients in a CSV reports.

we should probably have it schedule to get notify on the issue as when this situation occurs, rather then get the message expire itself..

###############################################
#MailQueue Ambiguous recipiets Monitor
#Author:Sunil Chauhan
#Email:Sunilkms@gmail.com
#site=sunil-chauhan.blogspot.com
#This scripts gets reports on Message stuck in Mail Queue due to Ambuguous Address Status.
#420 4.2.0 RESOLVER.ADR.Ambiguous; ambiguous address
#
###############################################

#Get all the Messages in Message Queue 

param ($EmailReport)

$to="to@domain.com"
$from="from@domain.com"
$smtp="mysmtpserver"
$csv="AmbiguousAdd.csv"
$Sub="Mail Queue Alert:RESOLVER.ADR.Ambiguous Status Found in Mail Queue"

$Msg = Get-TransportServer | Get-Queue | ? {$_.Messagecount -gt 0} | Get-Message -IncludeRecipientInfo
$dup = $msg | ? {$_.LastError -like "*420*"}
$details = $dup | select Status,FromAddress, @{n="Emailto";e={$_.Recipients | select -ExpandProperty Address}},LastError
$new = $details | select -Unique Emailto
$rec = $new | % {Get-Recipient $_.Emailto }
$report = $rec |select DisplayName,RecipientTypeDetails,SamAccountName,PrimarySmtpAddress,OrganizationalUnit,WhenCreated,WhenChanged
$report | Export-csv $csv -notype
ipcsv $CSV | ft -auto

if ($emailReport)
{
 $a = "<style>"
 $a = $a + "BODY{background-color:white;}"
 $a = $a + "TABLE{border-width: 20px;border-style: solid;border-color: black;border-collapse: collapse;border-spacing: 15px;}"
 $a = $a + "TH{border-width: 2px;padding: 8px;border-style: solid;border-color: black;background-color:#d5ebf5;text-align:center;}"
 $a = $a + "TD{border-width: 2px;padding: 8px;border-style: solid;border-color: black;background-color:#f8faf6;text-align:center;}"
 $a = $a + "</style>"

 $sub="RESOLVER.ADR.Ambiguous Report"
$body=@"
 <p>Mail Queue Alert:RESOLVER.ADR.Ambiguous Status Found in Mail Queue</p> <p>Total Emails Stuck in Queue with Ambiguous Error Status= $(($Details).count)</p>
 <p>Total unique recipiets = $(($new).count)</p>

        <p>Please fix the Recipients with Errors ASAP</p>
 $($details | ConvertTo-Html -head $a -PreContent "<p>Below Mails are stuck in the Queues with RESOLVER.ADR.Ambiguous Status.</p>"| Out-String)
 </br>
 <p>For more details on Recipients, please find the attached report and fix the recipients.</p>
"@
 
Send-MailMessage -To $to -From $from -SmtpServer $smtp -Subject $sub  -body $body -BodyasHTML -Attachments $CSV
}