So we’ve had a problem at work for awhile and I hadn’t been able to come up with a good solution until today.
Problem:
We have a person that works for us for a period of time and they leave the company. When they leave we start by expiring their AD Account for 30 days. After 30 days we remove the AD Account from our system. Most of the time this is fine, but every once in awhile we have that same person return to the company. So we create a new AD account and Exchange mailbox for them.
What happens now, is someone tries to send an email to the returning person, but gets and NDR saying the user cannot be found. The sender starts a new email and starts to type the name of the returning employee. The name pops up in Outlooks AutoComplete list and the sender selects the name, types their message, and hits send. At this point the NDR is generated and looks similar to the following (some information has been left out or changed):
– – – – –
John Smith (john.smith@domain.com)
The email address you entered couldn’t be found. Please check the recipient’s email address and try to resend the message. If the problem continues, please contact your helpdesk.
Diagnostic information for administrators:
Generating server: exchange.domain.com
IMCEAEX-_o=organaization+20name_ou=first+20administrative+20group_cn=recipients_cn=john.smith@domain.com
Remote Server returned ‘550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found’
– – – – –
Background:
This problem occurs because Outlook uses the LegacyExchangeDN attribute to populate the AutoComplete list. Because the original account was removed and a new account has been created the LegacyExchangeDN field is different. Apparently Outlook caches this attribute for people within the same Exchange Organization.
Solution 1: Remove entry from AutoComplete List.
Have the user start a new email to the returning employee. When they start to type the name in the To: box and they see the entry in the AutoComplete list, delete the entry. Then close the new message without saving it. Create a new email and type the returning employees name in the To: box. This will cause Outlook to pull the information from the Global Address Book.
The problem with this is it has to be done individually for every person in the Exchange environment that had emailed the returning employee prior to the the time they left the company.
Solution 2: Add a new X.500 address to the mailbox
To do this you first need to clean up the information from the NDR. To do this we will start with the “IMCEAEX-_o=organaization+20name_ou=first+20administrative+20group_cn=recipients_cn=john.smith@domain.com” line.
First replace all underscores (“_”) with a forward slash (“/”). Next replace all of the “+20″‘s with spaces. Now remove “IMCEAEX-” from the beginning of the line. Finally, remove the “@domain.com” from the end. The new line should look like this:
/o=organization name/ou=first administrative group/recipients/cn=john.smith
Copy that line and open up Exchange Admin Center. Find the returning employees mailbox. Edit the mailbox to add a new email address. You will need to select the custom option and set it to “X500” (no quotes). Then in the email address box paste the cleaned up line from above.
This should resolve the NDR problem for everyone in you Exchange organization.
I have struggled with this problem for a number of years, so I hope this will help others out too.
Source: Microsoft
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