LegacyExchangeDN / x500 Addresses

Target Audience:  Hosted Microsoft Exchange Users

Things you need to know if you are moving from an external Exchange environment to Rackspace's Hosted Exchange 2007

An Exchange server  uses an internal addressing scheme that routes messages  between mailboxes it hosts. These addresses are known as LegacyExchangeDN addresses or they are sometimes referred to as x500 addresses. When you send and receive messages on your current providers Exchange service these LegacyExchangeDN addresses are saved with sent and received messages in your inbox.  They are also saved within your AutoComplete cache in Outlook.  When you reply to or forward existing emails that are migrated over to our system, without first importing the x500 addresses, a bounce will likely be returned if Outlook uses the old x500 address.  The bounce will resemble the following non-delivery report:
Diagnostic information for administrators:
Generating server: IAD2HUB06.mex02.mlsrvr.com
#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##
If you still have access to your old Exchange server, you or your current provider will need to export your LegacyExchangeDN and provide the CSV file to us via a support ticket.  We will then get our Exchange engineering specialists to upload the LegacyExchangeDN export into our environment.  This will ensure that when you reply to or forward existing messages, even if the x500 is referenced, it will deliver to the correponding mailbox.  For a quick reference the following can be keyed into a Exchange server to retrieve the legacy data:

The following CSVDE (Comma Separated Value Data Exchange) command will need to be run from your Exchange server: 
csvde -d "OU=domain.com,OU=Hosting,DC=exchange,DC=rackspace,DC=com" -l mail,legacyExchangeDN -f x500.csv 

Everything within the quotes in the CSVDE command example needs to be the OU where your users reside, and that depends on your OU structure in your Active directory.  If you open ADSI Edit (you can run the command adsiedit.msc to open this tool) on the Exchange server, right click on the OU where all your users reside (Users, by default) and view the value of the distinguishedName attribute and that will be what needs to go in the quotes. Just replace everything in quotes with that OU, then hit enter, and it will export your addresses into a csv file saved to the location that you are currently in.  Once your Exchange mailboxes have been created our system, you will need to send this csv file to us attached in a support ticket and request that we import these LegacyDN addresses into your mailboxes.