This entry comes from http://blogs.technet.com/scottschnoll/archive/2006/12/31/exchange-2007-platforms-and-product-keys.aspx but I wanted to make a copy of it as its a useful post.
People are wondering what are the differences between the 32-bit and 64-bit version of Exchange 2007, what are the differences between the Standard and Enterprise Editions of Exchange 2007, particularly on the 32-bit version. People are also wondering what they can do with the trial version of Exchange 2007 posted for download on microsoft.com.
Editions and Licenses
First, let's talk about editions. Exchange 2007 comes in two server editions: Standard Edition and Enterprise Edition. These editions are described and compared at http://www.microsoft.com/exchange/evaluation/editions.mspx. As you can see in the Exchange 2007 Edition Offerings table on that page, the primary differences are:
Only the Enterprise edition can scale to 50 databases per server; the Standard edition is limited to 5 databases per server.
In a production environment, only the Enterprise edition is supported in a Windows failover cluster; the Standard edition is not supported in a Windows failover cluster in production; therefore, Single Copy Clusters and Cluster Continuous Replication are only supported on the Enterprise Edition. Notice that I said supported in production. More on this in a bit.
Even though Exchange comes in two edition offerings, these are licensing editions only, and controlled by the use of a product key. There is a single set of binary files for each platform (one for x64 systems, and one for x86 systems), and the same binaries are used for both editions. It is when you enter a valid, licensed product key that the supported edition for the server is established.
Note One important nuance of product keys is that they are for same edition key swaps and upgrades only, and they cannot be used for downgrades. You can use a valid product key to go from the evaluation version (Trial Edition) to either the Standard Edition or the Enterprise Edition; you can also use a valid product key to go from the Standard Edition to the Enterprise Edition. You can also re-license the server using the same edition product key. For example, if you had two Standard Edition servers with two keys, but you accidentally used the same key on both servers, you can change the key for one of them to be the other key that you were issued. These things can be done without having to reinstall or reconfigure anything. Simply enter the product key and restart the Microsoft Exchange Information Store service and the edition corresponding to that product key will be reflected. However, you cannot use product keys to downgrade from the Enterprise Edition to the Standard Edition, nor can you use them to revert back to the Trial Edition. These types of downgrades can only be done by uninstalling Exchange 2007, reinstalling Exchange 2007, and entering in the correct product key.
Exchange 2007 also comes in two client access license (CAL) editions, which are also called the Standard Edition and the Enterprise Edition. You can mix and match the server editions with the CAL editions. For example, you can use Enterprise CALs against the Standard server edition. Similarly, you can use Standard CALs against the Enterprise server edition. The Enterprise CAL is an additive CAL, which means that you buy the Standard CAL, and then add on an Enterprise CAL on top of it. An Enterprise CAL gets you all of the features listed in the last column of the Exchange 2007 CAL Offerings table (note that, as that page says, some of the listed features can only be purchased through a volume license program, and they are not available as retail purchases).
When you're ready to buy Exchange 2007, visit http://www.microsoft.com/exchange/howtobuy/default.mspx for details. BTW, please note that the above text is my interpretation of what is stated at http://www.microsoft.com/exchange/evaluation/editions.mspx as of 12/31/06, and my interpretation could be totally wrong. I encourage you to read the page yourself, and if you have any questions, feel free to contact Microsoft Sales using the contact information listed at http://www.microsoft.com/exchange/howtobuy/default.mspx.
32-bit vs. 64-bit
Next, let's answer the platform question: why is there a 32-bit version and a 64-bit version of Exchange 2007? We are working on some product documentation that will provide complete details, but until then, I've compiled a bunch of information that should answer all of the questions I've seen on this issue. We made two platform versions of Exchange 2007 with the intent that one platform version (the 64-bit version) would be used in production environments and the other platform version (the 32-bit version) would be used in non-production environments (such as labs, training facilities, demo and evaluation environments, etc.). You cannot purchase 32-bit version; you can only purchase the 64-bit version. Everyone should know the difference between a production and non-production environment, but in case you don't, KC Lemson and Paul Bowden give a great description of what we mean here in their Exchange Queue and A debut article for TechNet Magazine at http://www.microsoft.com/technet/technetmag/issues/2007/01/ExchangeQA/. As KC and Paul also explain, the lines between production and non-production use of the 32-bit are a little blurred, because we do allow minimal supported use of 32-bit code in production environments. Specifically, as they state, you can use the 32-bit version in production to administer Exchange 2007 servers and extend your Active Directory schema. All other uses of the 32-bit version of Exchange 2007 in production environments is unsupported. At this time, you cannot use either the 32-bit version or the 64-bit version on Windows Vista, or on Windows Server codenamed "Longhorn". One reason is that the Exchange management components (namely the Exchange Management Console and the Exchange Management Shell) rely on Windows Powershell, and at this time there is no RTM version of Windows Powershell for Vista or Longhorn. See http://www.microsoft.com/windowsserver2003/technologies/management/powershell/download.mspx for some details on the RTM version of Windows Powershell for Vista and Longhorn.
While the 64-bit version can be the Standard Edition or the Enterprise Edition, the 32-bit version is always and only the Standard Edition. As I mentioned earlier, Single Copy Clusters (SCC) and Cluster Continuous Replication (CCR) are only supported in production on the Enterprise Edition of Exchange 2007; however, we have made an exception in the 32-bit version code to allow SCC and CCR to be used for non-production use on the 32-bit version, even though the 32-bit version is the Standard Edition. This means that you can set up a 32-bit test lab for trying out SCC and CCR in non-production environments. Because its 32-bit, you can even create the non-production environments using Microsoft Virtual Server. I use Exchange 2007 in virtual environments for all of my blogcasts, Webcasts, demos, etc. and it works really well. If you're not sure how to build up such an environment, check out my step-by-step instructions. Also, check out http://msexchangeteam.com/archive/2006/08/09/428642.aspx for a blogcast on CCR that uses a virtual environment.
Note We also allow you to install Unified Messaging (UM) with the 32-bit version so you can check out UM-related features in a non-production environment. You can even use the software-based UM Test Phone described at http://www.microsoft.com/technet/prodtechnol/exchange/e2k7help/08e67a99-e37f-4afd-bd58-455b62580af7.mspx.
Exchange 2007 and Virtualization
Speaking of virtual environments and production environments be aware that it will be quite some time before Exchange 2007 is supported in production in a virtual environment. Virtual server support for Exchange Server 2007 is only supported in production using the 64-bit version, and neither Microsoft Virtual Server nor Microsoft Virtual PC support 64-bit guest systems. Our first 64-bit guest support will come with Hypervisor, which is coming for Longhorn within 180 days of Longhorn's release (note that is within 180 days, meaning, it could ship the same day as Longhorn, or it could ship 180 days after Longhorn ships). Exchange 2007 does not yet support Longhorn server (nor does it support Longhorn directory servers, so AD sites with Longhorn directory servers need to be isolated from AD sites that include Exchange 2007 servers). Support for Longhorn will arrive in a service pack (most likely SP1) for Exchange 2007. In summary, there won't be virtualization support for Exchange 2007 in production for some time.
Evaluations and Product Keys
When you install Exchange 2007, it is unlicensed and referred to as a Trial Edition. Unlicensed (Trial Edition) servers appear as the Standard Edition, and they are not eligible for support from Microsoft Product Support Services. The Trial Edition expires 120 days after the date of installation. When you start the Exchange Management Console, if you have any unlicensed Exchange 2007 servers in your organization, Exchange will display a list of all unlicensed Exchange 2007 servers and the number of days that are remaining until the trial edition expires. If you have expired unlicensed Exchange 2007 servers you will also see a separate warning for each expired server. For lab, demo and test environments, unless you have a valid reason for rebuilding the environment, or unless you just love our new Setup wizard so much that you just can't stop uninstalling and installing server roles, I recommend that you get used to dealing with the expiration nag dialog, and not rebuild your servers every 120 days. Either way, the choice is yours, but again, you won't lose any functionality when running on an expired Trial Edition.
You can upgrade from a 64-bit Trial Edition to a 64-bit retail version by purchasing the appropriate license(s) and by entering the Product Key that you get when you make the purchase. You can find the product key on the Exchange 2007 DVD case. It's a 25-character alphanumeric string, grouped in sets of five characters separated by hyphens. Step-by-step instructions for entering your product key can be found at http://www.microsoft.com/technet/prodtechnol/exchange/e2k7help/40d9e583-69cd-4363-807f-43e02e03ca78.mspx. These steps include instructions for entering the key using either the Exchange Management Console or the Exchange Management Shell. However, in the 32-bit version, there is no Exchange Management Console interface for this because you can't purchase 32-bit licenses.
Using either the Exchange Management Console or the Exchange Management Shell, you can see what Edition you're running, and using the Exchange Management Shell, you can also see how many days, hours, minutes, seconds, and yes, milliseconds, are left on the 120-day trial period. Use the Get-ExchangeServer cmdlet and look for the Edition and RemainingTrialPeriod values.
What's Missing from the 32-bit Version
There are some things that are not available in the 32-bit version:
Automatic Anti-spam updates from Windows Updates. Only a licensed 64-bit version will be able to get automatic anti-spam updates from Microsoft Update.
Storage groups and databases. You can have a maximum of 5 databases per server in as many as 5 storage groups on the 32-bit version.
