XADM: Home Server Appears Incorrectly After You Create a Child Public Folder on an Exchange Server (812289)

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When you create a child public folder on an Exchange 2000 Server-based computer where that server does not contain a replica of the parent public folder, a temporary replica of the public folder is created on the Exchange 2000 Server. When replication occurs between the Exchange 2000 Server-based computer and the Exchange Server 5.5-based computer, the temporary replica is re-homed to the Exchange Server 5.5-based computer.

This process includes the following two parts:

• The Exchange 2000 Server chooses a new server on which to home the public folder, and then sends an update message.
• The new home server receives this message, and then re-homes the replica.

The issue that is described in the "Symptoms" section of this article occurs because the homeMDB attribute is written by the Active Directory Connector (ADC) to the Exchange 5.5 Server Directory Service (DS) and not the Information Store. The ADC does not know about the replica lists that are held by the Exchange 5.5 Server but only knows about the site where the public folder is homed. The ADC randomly picks a public folder store from that site, and then writes that as the value of the homeMDB attribute in the Exchange 5.5 DS.

Note The ADC only writes the homeMTA and homeMDB attribute values during its initial replication of the public folder instance.

The homeMDB attribute is used for two functions:

• To limit administrative access to the home site.
  
  Because the value of the homeMDB attribute assigned by the ADC points to a server in the same site as the replica, it does not adversely affect the administrative access.
• To permit e-mail delivery to public folders.
  
  Because the value of the homeMDB attribute assigned by the ADC points to a server in the same site as the replica, the public folder store can look up the replica list to find the e-mail destination.

Important Because the ADC randomly determines the value for the homeMDB attribute, you must be careful about removing public folder replicas from the site during the migration process to Exchange 2000 Server.

Microsoft recommends that you move public folder replicas off of Exchange Server 5.5-based servers and on to Exchange 2000 Server-based servers in the same site. Before you remove the replicas from the site, switch the Exchange 2000 Server organization to native mode or at the least make sure that you have public folder affinities in place to permit uninterrupted e-mail delivery. You must do this because you can potentially have the homeMDB attribute value point to a different site than where the public folder replica exists. In this case, Exchange Server 5.5 requires public folder affinity set up to the remote site to see the replica.

Removing the Last Exchange 5.5 Server in a Site

When you delete an Exchange Server 5.5-based server in a site, any folders that are homed on this server get re-homed to another server in the site on the replica list. However, when you remove the last Exchange Server 5.5 from the site, there are no servers left to re-home the public folder. The ADC does not re-home the public folder because it does not have an Active Directory attribute that directly corresponds to the homeMTA and homeMDB attributes. Additionally, the ADC only writes the homeMTA and homeMDB attribute values on its initial replication of the public folder.

Because of this, you may have homeMTA and homeMDB attributes that point to non-existent servers. In this scenario, you must perform a complete re-replication of the public folder connection agreement in the site where you experience this issue. This forces the ADC to rewrite the homeMTA and homeMDB attributes. However, because there are no Exchange Server 5.5 servers to select from, the Site Replication Service (SRS) or the Exchange Server 5.5 Directory Service with which the public folder connection agreement communicates is used to replicate the updated information to the other Exchange Server 5.5 servers.

To restate this, when the last Exchange Server 5.5 public folder server has been removed from the site, resynchronize your public folder connection agreement so that the homeMTA and homeMDB attributes are set to an Exchange 2000 Server. This information is then replicated to the Exchange Server 5.5 Directory Service by using the SRS.

Note Microsoft recommends that any connection agreements point to the SRS in a mixed-mode site. As soon as an SRS is in a site, it is best to configure all connection agreements in that site to point to the SRS.

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