We have all been there. At some point in our lives we needed to migrate a mailbox from one place to another. And although migration processes are normally pretty straightforward, the shizzle starts to hit the fan when the end-user gets involved.

Let me paint this picture for you:

Recently I was asked to migrate an Exchange 2007 mail-enabled Public Folder Folder to an Exchange 2013 shared mailbox. Nothing scary there. Just your run-of-the-mill PST migration.

After finishing the migration and adding the newly created shared mailbox to Outlook clients, users started to complain that when other users wanted to email them they would get an NDR saying: Email-address or user not found.

You probably guessed it: The cause being of course the Outlook Auto-completion cache.

Now I could have just emptied the cache of every last Outlook client and be on my happy way,  but instead I dug a little deeper and found this little gem of an article:

Mystery of adding X500’s – What an amazing thing to know…!!!

All credits go to the author of this article, because it made my life easier. In this article the cause of the NDR becomes evident. In it it is explained that in the Outlook cache the X500 address of the original Public Folder is retained. This address points to the Active Directory object of said Public Folder. To point Outlook in the right direction, we could just add the original X500 address to the new shared mailbox.

How this is to be done is pretty simple:

  • Open the NDR report received by any sender and copy the line with the X500 address:
    • 1-NDR
      • The original line is longer than above example, so make sure to copy the complete line!
    • Paste it in your favorite text-editor.
    • Remove the first part (IMCEAX-)
    • Replace all _ with /
    • Note the +20, +28 and so on in the line. Replace these with their corresponding punctuation marks.
      • +20 = space
      • +28 = (
      • +29 = )
      • +2E = .
    • The result being something like this (parts removed to protect myself):
    • Now all you have to do is add this line as an X500 address to your shared mailbox.
      • 2 - addaddress

Enjoy this little bit of knowledge to ease your e-mail migration days!

Happy administering!