One of our users was having exchange difficulties so I got the bright idea of moving their messages off to a PST file and then deleting their profile and making a new one then transferring the messages back. It all worked out great and it even seemed to fix some problem, but now if anyone replies to a old email there is a send error as exchange can't seem to find the user anymore despite being setup with the exact same name/email. Is there a way to add some kind of alias or something that would fix this problem? My guess is that there is some kind of unique identifier that wasn't duplicated but I really don't know.

I have access to their account before it was deleted. So I can look up settings.

1 Answer 1


The legacyExchangeDN may have changed. This is the address that outlook is holding on to in the old emails, as well as the cached address book entries that are autofilled when they try to email the person. You can add the old value which looks like this:

/o=Organisation/ou=Administrative Group/cn= Recipients/cn=Username

back to their account as another x500 address (some of that is shown here):


You'll have to get the old legacyExchangeDN (x500) address, which I think comes back to you in the bounceback you get when someone replies to the old account. It should say something like "couldn't find "/o=Organisation/ou=Administrative Group/cn= Recipients/cn=Username" ... Just add that to their account. Maybe the new mailbox is in a different group or something so the legacyExchangeDN changed...

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    +1 - Ya' beat me to it. Oct 22, 2010 at 16:49
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    +1. You both beat me to it. If the user account was deleted and then recreated then the legacyExchangeDN would without a doubt be different. Outlook uses the legacyExchangeDN to reply to internal emails. Adding the legacyExchangeDN as an x500 address is definitely the fix.
    – joeqwerty
    Oct 22, 2010 at 16:54
  • Thanks, that did it. I had seen articles about the x500 option, but nothing explained it as well as this. THANKS!!!
    – Nori
    Oct 22, 2010 at 18:39
  • Man you beat Evan Anderson to it...... if I could give +2 I would. :-p Oct 22, 2010 at 19:09
  • Had my finger on the trigger... :)
    – Matt
    Oct 22, 2010 at 23:07

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