X.500 NDR’s – Fix vs. Clear Cache

Customer raised a ticket to me a few weeks ago for an NDR I know well. An NDR I normally respond to by telling the customer to clear their NICK NAME or Autocomplete or NK2 cache, whatever you learned to or want to call it. I tell users they can use the outlook switchoutlook /cleanautocompletecache to clear their cache
or they can find the name in the autocomplete drop box in Outlook or OWA, click the black X next to the name, and delete the name from the cache; problem solved.

Well, the specific customer did not want to do that – they wanted to pay me triple digits an hour to make the invalid address work for all of their users vs. asking their users to do something. Who am I to object to more money. I know what needs to be done, but have never actually done the fix before.


The valuable details in the NDR are below

#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##7

The NDR says no such address, which is true. The address is wrong based on client Nickname cache for the sending not being updated for a moved user. The Nick name cache stores addresses in X.500 format. The X.500 address have the Exchange organization name in them and the org name changes when you move to different Exchange versions, Your servers moves to a different OU, or you migrate to new Exchange orgs, and the old address does not come with the object. In the case of this issue we moved the user to Exchange 2016 causing the NDR.

The words in the NDR do not add up to true official X.500 address. They have 20 and 2C
asci character codes in them and they are missing slashes. I did some interneting and found me a KB covering how to convert the NDR into the official X.500 address – https://support.microsoft.com/en-us/kb/2807779 Based on the KB I created the below X.500 address needed to be add to the user object


Add the Address to the Object

The email address attribute on a mailbox object has a bucket of addresses in a string. When you add an email address to a mailbox and only included the address you overwrite everything in the address field and end up a sad face; yeah string. To avoid the sad face overwrite I’ve always used the @{add= to add to the emailaddresses field vs overwriting it. Much like the command below.

get-mailbox kev | set-mailbox -emailaddresses @{add=”X:500:/O= KEV LIFE_OU=EXCHANGE ADMINISTRATIVE GROUP (FYDIBOHF23SPDLT)/CN=RECIPIENTS/CN=Miller, Kev”}

or you could do it the long way around with something like that below command using a few varibles

$bob = get-mailbox kev
set-mailbox $bob.name -emailaddresses $bobplus


Every post needs a picture, but I can’t think of a great picture to include here other than the NDR itself which has PII customer data in it and is not postable //sooo// Here’s a shot of Maddex and I in the lab working on a millennium falcon Lego set # 75105 – the directions and parts bags came in a 20# box of random Lego parts momma bought a while back. No box for the falcon, so we did not resell it, and were forced to build it. At 1,329 pieces it’s been taking us a bit to finish. Hope we’re done next week.

List of projects we’ve played with in the lab so far this year — http://www.happymillfam.com/lab-journal-2016/

Momma bought us lab jackets for my birthday this year.

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