This scripts clears the attribute legacyExchangeDN if set to ADCDisabledMail

Clear-ADCDisabledMail.ps1

# This script clears the legacyExchangeDN attribute of AD objects if the attribute is set to ADCDisabledMail

# Active Directory search base, adjust as needed for your AD 
$SearchBase = 'DC=VARUNAGROUP,DC=DE'

# Our search filter
$Filter = 'legacyExchangeDN -eq "ADCDisabledMail"'
$csvFilename = 'ADCDisabledMail-Users.csv'

# Search for user objects matching the filter in the defined search base
$affectedObjects = Get-ADObject -Filter $Filter -SearchBase $SearchBase 

# Some output
Write-Host ('{0} object(s) with legacyExchangeDN = ADCDisabledMail found' -f ($affectedObjects | Measure-Object).Count)

# Export users for documentation purposes
if(($affectedObjects | Measure-Object).Count -gt 0) {
    $affectedObjects | Export-Csv -Path $csvFilename -Encoding UTF8 -NoTypeInformation -Force 
    Write-Host ('Object information exported to {0}' -f $csvFilename)


    # Clear the attribute
    $affectedObjects | Set-ADObject -Clear 'legacyExchangeDN'

    Write-Host ('legacyExchangeDN cleared for {0} object(s)' -f ($affectedObjects | Measure-Object).Count)
}
else {
    Write-Host 'No user objects found with legacyExchangeDN = ADCDisabledMail'
}