I already blogged earlier about the multi-tenant hosting possibilities in Exchange 2010 SP1 when using the /hosting switch during installation. This provides a true multi-tenant Exchange 2010 environment but lacks quite an amount of functionality, like Public Folders, the Unified Messaging Role, Lync Server 2010 multi-tenant integration (although an update on this is expected later this year) and provisioning difficulties. You can read my two earliers blog post on Exchange 2010 hoster edition and Exchange 2010 SP1 hosting & Control Panel. Although it is doable, it is difficult at the same time.
With the upcoming Service Pack 2 for Exchange 2010 there’s nothing new with respect to the Hoster Edition, but for a normal installation (also referred to as on-premises installation) a new feature called Address Book Policies (ABP) will be presented. The new ABP feature is the successor of the Exchange 2007 Address List Segregation (which is not supported in Exchange 2010 since it might horribly break Exchange 2010). This makes it easier for non hosting customers to implement multiple address lists without using the /hosting switch (please remember you need to be a registered hoster to officially use the hoster edition of Exchange 2010 SP1).
Personally I have implemented the hoster edition of Exchange 2010 SP1 at several hosting customers. Although I do see the possibilities and added value of the hoster edition I also see the disadvantages like the complexity, the need to write your own provisioning tools and the lack of features.
I also have implemented Exchange 2010 running in on-premises mode (i.e. a regular installation) in hosting environments where the multi-tenancy was enforced by a 3rd party Control Panel vendor. In a scenario like this all features that are not supported by the hoster edition of Exchange 2010 SP1 are officially supported by Microsoft and the 3rd party vendor.
It is my personal believe (you mileage may vary of course) that on the long term customer are better of using an on-premises installation of Exchange 2010, integrated with a 3rd party Control Panel vendor. If there’s more time available it’s worth the time waiting for Exchange 2010 SP2 and start looking at the Address Book Policies.
3rd party Control Panel vendors that Microsoft works closely with (with respect to hosting Exchange Server 2010) are:
- Parallels Automation Microsoft Exchange Service Module
- Ensim Unify Service Provider Edition
- Cortex control panel from Citrix for delivering hosted Exchange
- Extend ASP for hosting Exchange
Besides my own personal opinion Microsoft is shifting its support stance as well. There a blog post from the Exchange Partner Marketing team, based on a presentation from the Microsoft Worldwide Partner Conference (WPC) called So, you want to host Exchange
The Microsoft Exchange team also blogged about this issue, referring to the upcoming Address Book Policies: Exchange Server 2010 SP2 and Support for Hosting Exchange
These days I do not recommend anymore using the Hoster Edition but stick with a 3rd party Control Panel vendor and have the full package completely supported.