Message and Calendar items that are migrated from one domain to another will not be able to be modified or replied to because the X500 addresses from the original Exchange server cannot be resolved from the new Exchange server. This of course can cause a major amount of frustration for the administrator and end users. Therefore mailboxes being migrated between domains will need to have the LegacyExchangeDN from the source domain added to the mailbox in the target domain. This makes sure that when a user replies to or modifies a message or calendar item originating from before the migration, that the LegacyExchangeDN information can be resolved to a valid X500 address.
NOTE: This will only be a problem for historic emails and meetings, not new messaging items
Below are some articles about this problem and how to resolve.
NOTE: The LegacyExchangeDN tool is not really needed it just makes some of the change processes a bit easier than using ADSIEdit as outlined below
Below is the general outline of how to address this issue:
WARNING: ADSI Edit is a very powerful utility that should be used with extreme caution and
Lucid8 is providing the information herein as sample reference material as a courtesy and does not recommend or warrant the use of ADSI Edit.
If you use the ADSI Edit snap-in to make modifications and incorrectly modify the attributes of Active Directory objects, you can cause serious problems.
If you choose to utilize ADSI Edit to modify attributes of objects within Active Directory you do so at your own risk.
Using ADSIEdit or the LegacyExchangeDN tool lookup the historic users LegacyExchangeDN to get the prefix before the mailbox name.
We recommend that you create a sample mailbox and test the process before proceeding with modifications to production users.
That said what you will want to do is:
Copy the existing LegacyExchangeDN to create as an x.500 address
Then modify the existing value to reflect the proper name and add the address.
Source user LegacyExchangeDN: /o=L8/ou=First Administrative Group/cn=Recipients/cn=User1
Target email address to be added: X500: /o=L8/ou=First Administrative Group/cn=Recipients/cn=User1