PowerShell-Bulk Export & Import of X500

One of the most important thing to take care is the X.500 Address when you are doing Direct Cut Over migration from Microsoft Exchange Server to a new Exchange Server in different AD Domain or Office 365

The X.500 Address is used by Microsoft Outlook to identify users (NOT SMTP Address) within Exchange Organization (Refer to the http://www.askme4tech.com/exchange-server-x500-address-amazing-thing-know for more detail information.

Please refer to the steps below on how to export & import X.500 using PowerShell Script
To export the ExchangeLegaceyDN from Source Domain. 

 Get-ADUser -SearchBase “DC=YOUR-DOMAIN,DC=COM” -Filter * -Properties SamAccountName,legacyExchangeDN | Select-Object SamAccountName,legacyExchangeDN | Export-CSV C:\Temp\Exported-LegacyDN.csv -NoTypeInformation

To Import to new Domain Controller. 

Import-Module ActiveDirectory
$Input = Import-CSV C:\Temp\Exported-LegacyDN.csv
ForEach ($ADUser in $Input){
if ($ADUser.legacyExchangeDN){
Set-ADUser -Identity $ADUser.SamAccountName -add @{proxyAddresses=”X500:$($ADUser.legacyExchangeDN)”}
}
}

All credits:

https://aventistech.com/2018/07/powershell-bulk-export-import-of-x500/

Source for the Script.

https://www.petenetlive.com/KB/Article/0001468

This describes my exact issue:
https://www.tipsdotcom.com/recipient-not-found-by-exchange-legacy-encapsulated-email-address-lookup.html