Microsoft reached Exchange Server 2013 and everyone one planning to go next level messaging system, there are many way to move your current Messaging environment (Exchange 2003/2007/2010) to Exchange 2013.
To transition from Exchange 2007 or 2010 environment to Exchange 2013 requires that you upgrade Active Directory schema with the new changes for Exchange 2013. Then you need to install Exchange 2013 itself, install certificates, move the existing CAS namespace to the new CAS server, and make a bunch other adjustments. But none of these are why you can't upgrade to Exchange 2013.
The problem is with Exchange 2007 and Exchange 2010 more precisely, in coexisting with them. Exchange 2007 needs a special roll-up to work with Exchange 2013, and Exchange 2010 needs Service Pack 3. Even if your goal is to fully replace Exchange 2007 or 2010 with Exchange 2013, you need the new and old versions for at least a transition period. Neither update exists yet, so you can't migrate to Exchange 2013.
The sad fact is that Microsoft provides no way to migrate/upgrade Exchange 2003 directly to 2013 at this moment. It doesn’t mean, however, you are left with no options if you would like to move straight to the newest version of Microsoft’s email platform. There are several solutions you can consider. The first one is the “double hop” migration.
Double hop migration
Double hop migration you either will have to migrate twice, once from Exchange 2003 to Exchange 2007 or 2010, then again to Exchange 2013. This method requires double to work and have risk of the process going way. It also require some resources like hardware or virtual machines, only to host the temporary environment before moving it to the target location and most important part is the entire operation must be planned and done with very care to reduce the downtime.
Export and Import PST option is good for small organization for Migration from Exchange 2003 to Exchange 2013, as you know it is not simple as it like obviously it will take much time to migrate PST from one environment to another environment.
First of all manually added legacyExchangeDN X.500 address and re-imported Exchange 2013 and user will not able to use their email in normal way and also it will add some extra work to entire migration process and risk will be some time services not available during migration.
Another critical issue while using Export/Import PST option is Public Folders. If you using same way to re-importing Public Folder in to the target location will not recreate the folder permission and you will have to have set them manually.
3rd Party Migration tool
As you know Microsoft does not have plan any co-existence of these two versions. If you want direct move to Exchange 2013, you need third party migration tool which will migrate your Exchange environment smoothly. Good news is Dell/Quest Software “Quest Migration Manager” for Exchange will support a single hop migration from Exchange 2003 to Exchange 2013 in Inter-Org Exchange migration scenarios directly without the requirement of a transition server. When you're preparing the migration, be sure to run Microsoft's Web-based Deployment Assistant to see the current recommended steps for your configuration.
In this series I’m going to transition/migration from Exchange Server 2010 to Exchange 2013 as I mention in above transition from Exchange 2007 or 2010 environment to Exchange 2013 requires that you upgrade Active Directory schema with the new changes for Exchange 2013. For complete a migration from Exchange 2010 to Exchange 2013, we need to introduce Exchange 2013 into your existing Exchange environment, then migrate our content onto the new server(s), and finally remove Exchange 2010.
In this series I have my own existing Exchange 2010 environment running on Windows Server 2008 R2 SP1 and holding all roles (Mailbox, Client Access and HUB transport) I’m putting in two Exchange 2013 onto a new server Windows Server 2008 R2 SP1 which will part of the high availability (DAG). Post install the new server will hold Mailbox and Client Access Server roles.
As you know unless you have Microsoft “Software Assurance” you can’t upgrade to Exchange 2013 without any cost. No doubt you have to buy the Exchange 2013 base product and you may look at an “Open Value Agreement” which lets you pay the cost over a three year term. Exchange 2013 (On-Premises) comes in two flavors, Standard and Enterprise edition.
Standard edition for small business deployment which will hold max 5 databases and Enterprise edition for large Exchange deployments where we can create 100 databases.
Before we have two type of the CAL for Exchange Server 2013, this also called Standard and Enterprise. DO NOT get confuse that an Enterprise CAL is not for Enterprise Exchange edition and a Standard CAL is not for Exchange Standard edition.
Standard CAL required for all users/devices that require access to an Exchange mailbox.