Many organizations are in the process of migrating incrementally from Exchange 5.5 to Exchange 2000 or 2003. During this process, some previously unencountered issues in the way Exchange 5.5. and 2000/2003 deal with each other may come up.
One of the more common errors that can occur in a mixed 5.5/2000 environment (for instance, if one server is being used as a bridgehead) is logged as a category 9000 / 9004 error in the Event Log. The content of the error message varies. Sometimes it reads, "some malformed property of the recipient caused it to be NDRd," or "categorizer encountered a hard error while processing a message." The messages in question are not delivered (either inbound or outbound).
There are several possible reasons for this, either because of known bugs, misconfiguration or both. Here are four possible culprits and their solutions.
1. The domain settings for Internet message formats are not correct. This can happen if the domain-level settings for Internet message formats aren't properly specified— i.e., plain text vs. MIME. To set this for the domain, open the Exchange System Manager and go to Organization | Global Settings | Internet Message Formats. Ensure that one of the domains listed is configured as the wildcard (*).
2. One of the servers is referencing a server that was renamed or deleted, or some other Active Directory object that is now missing. This is usually the result when an administrator has to remove objects from Active Directory (AD) to complete an upgrade from an earlier version of Exchange, or if the previous server was not removed from AD properly. This causes other servers in the same domain to reference the deleted one. To fix this, run the Exchange Server Administrator and open all Exchange 5.5 servers in the organization. Under the server object, select the private information store, press Alt-Enter and then check the Public Folder Store to make sure it is pointing at a valid server. If it is, and you are still getting the same errors, switch it away to another server and then back to the original to insure that the correct AD information is being used.
3. There is a problem with inheritable permissions. If an Exchange Server object's permissions aren't valid, directory lookups can fail. To fix this, open the Exchange System Manager and get the properties for the Exchange 2000 object causing the error (usually the IMC). Under Properties | Security for the object, select "allow inheritable permissions from parent to propagate to this object" and click OK on any warnings you receive. Make sure this is the same for all other servers that might experience this problem.
4. A known issue in Exchange 5.5 SP3 involving encapsulated mail addresses can cause this. Another symptom of this particular version of the problem involves extremely delayed mail delivery. Microsoft has published a post-SP3 hotfix (see Knowledge Base article 824282 for this specific problem.
Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter.