邮件退信错误 #550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##

A week ago, one of our customers had a corrupt email account . Now they are using MS Exchange 2010, but they migrated to this solution a couple of months ago from MS Exchange 2003.
To fix the corrupted mailbox issue, we recommended them to export the valid emails, to delete the corrupted account, to recreate it and to import all the saved emails. Everything work as expected but soon some of their employees started to receive non delivery reports when trying to communicate with that person.
The reports look like:
The e-mail address you entered couldn't be found. Please check the recipient's e-mail address and try to resend the message. If the problem continues, please contact your helpdesk.
Diagnostic information for administrators:
Generating server: SERVER.contoso.com
IMCEAEX-_O=CONTOSO_OU=First+20Administrative+20Group_cn=Recipients_cn=mihaeladumitrache@contoso.com
#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##
This is an issue that I’ve seen before. The obvious reason for this is the fact that outlook client caches the emails recipients and when you try to send an email to such a recipient, the email client uses the cached LegacyExchangeDN instead the one from the Organization GAL.
Since it was a migrated account from Exchange 2003 to Exchange 2010, the old LegacyExchangeDN attribute was different from the one generated for the new account.
The new one looks like: /o=Contoso/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=username and the old one looks like: /o=Contoso/ou=first administrative group/cn=recipients/cn=username
A friend of mine (Brad Simionescu) that is working for that client came with an interesting idea:
- Remove the old disconnected mailbox
- Force the domain replication
- Using ADSI editor, replace the new LegacyExchangeDN with the old one
- Force the domain replication again
- Rebuild the Exchange address books
If somebody already downloaded the address book with the new LegacyExchangeDN, you have to follow http://support.microsoft.com/kb/287623 article to delete the new cached info and to download again the address book.