User unable to Send email, email bounce back with the below error:

Error :

To isolate the issue

1: Checked if the user is in Disabled account in Directory Services User & computers.

2: Checked if the user Mailbox has been migrated from Legacy Version to Latest version of Exchange.

As expected confirmed that the user has been Migrated from Exchange Server 2003 to Exchange 2010.

Then Quickly ran the below command and found the “LegacyDN” address.

 [PS] C:\>Get-Mailbox “Test1” | fl LegacyExchangeDN

LegacyExchangeDN : /o=Example/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=Test1

Any new e-mail sent from Outlook using the previously cached X.500 address was being rejected because the old X.500 address no longer existed in the organisation.

The solution to the problem is actually quite simple – add the old legacyExchangeDN X.500 address to the new mailbox as a proxy address.  You can add an X.500 proxy address through the Exchange Management Console, or the Exchange Management Shell.

To add the proxy address in the console, double-click the mailbox you need to add the proxy address to, go to the E-Mail Addresses property page, and add a new custom address:

 Steps:

Open ADSIEDIT.MSC -> Default configuration -> Expand Users Container

-> Locate to the User ID “Test1” -> Right Click -> Properties

-> Go to LegacyDN if your unable to find on the bottom click Filter and select “Show Only Attributes that have values”

Now you will find LegacyDN -> Edit -> copy the value in Notepad

Now go the User account in Exchange Management console -> Under Recipient configuration -> Add the X500 address as shown below.

Now the copied LegacyDN address past in Email address and Email type should be X500

Below is an Example:

Click Ok.

This technique can be used to solve this problem in a number of other scenarios where the legacyExchangeDN attribute has changed, and is not limited to mailboxes.

For example, if someone leaves the Exchange organization and you want their e-mail to go to an external e-mail address you would create a contact record with the necessary SMTP proxy addresses.  If you also added the legacyExchangeDN of the old mailbox to the contact record as an X.500 proxy address Outlook users wouldn’t get bounced messages if they used the old entry in their auto-complete caches.

Note : For Multiple users we can Use Ad modify tool

For More Info:

http://support.microsoft.com/kb/909271

http://techrid.com/category/exchange-server/mailflow/page/4/

Praveen Kumar

MCTS | Exchange Server