When upgrading from Exchange Server 2007 to Exchange 2010, Microsoft requires that you perform a clean Exchange 2010 installation onto a separate server and then migrate mailbox and public folder content to the new server. You can no longer perform an in-place upgrade.
Because of this, Exchange 2007 and Exchange 2010 must coexist from a short period of time while data is being migrated, to as long as “indefinitely.” No matter how long the coexistence lasts, many Exchange organizations experience unexpected issues during that time. Here are a few problems you may encounter and their fixes.
Edge transport server issues
There appears to be some confusion as to how the edge transport server works in an Exchange 2007/Exchange Server 2010 coexistence situation. When you deploy an Exchange 2007 edge transport server, you must create an edge subscription on your hub transport server. The edge subscription links the edge transport server to Exchange Server 2007’s transport pipeline.
Like Exchange 2007, Exchange Server 2010 also includes both a hub transport server role and an edge transport server role. During coexistence, an Exchange 2007 hub transport server resides alongside an Exchange 2010 hub transport server without any problems. And you can continue to use an Exchange 2007 edge transport server indefinitely.
However, things get tricky when you begin to phase out your Exchange 2007 servers. Exchange 2007 doesn’t allow you to uninstall the hub transport server role without first deleting the edge subscriptions that are bound to that server. When you delete these subscriptions, it has an effect similar to orphaning your edge transport server.
If you’re trying to phase out your Exchange 2007 servers, the method is to deploy an Exchange 2010 edge transport server. Not only can this server peacefully exist with your edge transport servers, but you can load balance SMTP traffic across multiple edge transport servers.
When you deploy your first Exchange 2010 edge transport server, it must be subscribed to an Exchange 2010 hub transport server. You can’t subscribe an Exchange 2010 edge server to an Exchange 2007 hub transport server.
Once you have two parallel edge servers and two parallel hub transport servers in place, you can change the MX record to point to your Exchange 2010 edge transport server. After verifying that mail flow is working, you can remove the edge subscription from the Exchange 2007 hub transport server and decommission both the Exchange 2007 hub transport and edge transport servers.
Issues when managing distribution groups
A common complaint after migrating to Exchange 2010 is that the new server breaks distribution group management. When a user opens Outlook 2007 and attempts to manage his or her distribution groups, he receive the following error message:
Changes to the distribution list membership cannot be saved. You do not have sufficient permissions to perform this operation on this object.
By default, Microsoft designed Exchange Server 2010 so that users cannot manage their own distribution groups unless they have specific permissions to do so. To give users the ability to manage their distribution groups, go into the Exchange Control Panel and follow these steps:
- Choose the option to manage My Organization.
- Select the User Roles option, which is found in the Users and Groups section.
- Select the Default Role Assignment Policy and click the Details button.
- Check the My Distribution Groups box