Auto complete, Reply-ability, I need my X500!!!!

Sometimes i join discussions regarding Exchange cross-org migrations and the most hot topics is always about migration planning, mailboxes content migration, user’s notification, outlook profiles, etc… but what about the below two important points:

· Outlook auto complete feature (Automatic Name Resolution). After migration of mailboxes users will got NDR if they send an email using the outlook auto complete feature

· Reply-ability to old emails. After migration of mailboxes users will receive NDR if they tried to reply to an old email that is received from a user in the same Exchange organization

Why is this happening? Simply Outlook stores the recipient information using the LegacyExchangeDN value of the user’s mailbox, so when you do the migration of the mailbox you actually migrated the SMTP address & the mailbox content but you didn’t migrate his LegacyExchangeDN…

So how can we solve this? Simply we need to copy the LegacyExchangeDN value of the users’ mailboxes as an X500 address so that Exchange can deliver these emails. I will highlight some of these migrations scenarios to see how we can solve this:

- In managed migrations where there is a GalSync solution between the two organizations using MIIS or ILM the GalSync will stamp the LegacyExchangeDN value of the mailboxes in the source organization as an X500 address on the contacts created in the target organization.

- In Exchange 2007 we can use the move-mailbox cmdlet to move mailboxes between different Exchange organizations knowing that the target must be an Exchange 2007 org. The move-mailbox process will do the migration of the LegacyExchangeDN value of migrated mailboxes and stamp it as an X500 address to relief us from this pain.

But what about non-managed migrations or between organizations who don’t have a connectivity between their data centers, in these type of migrations you have to extract the LegacyExchangeDN value from the source mailboxes and stamp it as the X500 address to the target mailboxes in the target organization. One of the approaches that you can follow is using CSVDE to extract a CSV file from the source organization (Exchange 2000 or 2003) and manipulate it to have only two columns (alias & LegacyExchangeDN) then use the below powershell script to stamp the X500 address on the target mailboxes created in the Exchange 2007 organization,

Import-CSV file.csv | foreach {

$Temp = Get-Mailbox -identity $_.alias

$Temp.EmailAddresses += “X500” + $_.legacyexchangedn

set-mailbox -instance $temp}

so by having the X500 address on the migrated mailboxes Outlook auto complete and reply-ability to old emails will work as usual because the address Outlook tells Exchange to use is still valid.