Imagine having multiple domains in multiple forests with multiple Exchange servers. Some of the domains are still running Windows 2003 domain controllers. Many of the desktops are running Windows XP. Microsoft Office was purchased OEM so end users have version running from 2000 to 2013. Several smaller business units are running Small Business Server 2003 while the larger use Exchange 2003 and 2007. You have about 1,000 users in multiple locations being managed by multiple IT departments.
And yes, it is 2014. Years of neglect have created this “diverse” computing environment. This may not represent your company but you probably have at least one of these issues to deal with if you need to upgrade your Exchange server. Doing nothing isn’t an option so what do you do?
Single Sign On
You probably want single sign on for your domain. Honestly, many of the features that make Office 365 useful work best with single sign on. Some of these steps can be avoided if you want your users to have one account for email and another to log into their computer.
Single Sign On will require Active Directory Federation Service to be installed and working in your domain or in the cloud. Once working, whatever username and password you use to sign into your computer are what you will use to sign in to your Office 365 account. When you disable an account in AD, it will be disabled in Office 365.
You can convert from Single Sign On to separate accounts but you cannot go from separate accounts to SSO. Decide early if SSO is important to you because there is no going back.
Office 365 is essentially Exchange 2013. You will need Exchange 2010 or better to migrate to Office 365. If you are running Exchange 2010, you may not need to do any more upgrading, if not, you will be installing Exchange 2013. That means your domain and forest have to be ready for Exchange 2013. The system requirements can be found here: http://technet.microsoft.com/en-us/library/aa996719(v=exchg.150).aspx
- you cannot install Office 2013 on Windows XP. This is probably good as it forces you to upgrade or replace all your Windows XP machines but it can be painful if you have a lot of them.
- Office 2007 is the earliest version that works with Office 365. (If you are buying Office 365 E3, you get a copy of Office 2013 for every user.)
- Office 365 requires Internet Explorer 9+ or other browsers. Again, you can’t run IE 9 on XP.
- Exchange 2013 cannot coexist with Exchange 2003 or earlier.
So, to use Office 365 or Exchange 2013, you must upgrade or replace your Windows XP machines with Windows 7 or 8. (Vista would work as well by why torture yourself?) You must also upgrade to Office 2007 or better or people will have trouble using email during the migration. Lastly, Exchange must be 2010 or later.
Although it appears that you could keep multiple domains in multiple forests, all the consultants I have talked to recommend against it. If you ended up with multiple forests through acquisitions or accident, this us the time to collapse into a single forest. Once you integrate into Office 365, it will be difficult collapse domains or forests.
In my early career, I was a consultant that specialized in Active Directory migrations. It has been years since I have done one and things have changed. Unless you do Active Directory migrations all the time, I suggest hiring a high quality consulting firm to help.
Once your domain and forest are running in Windows 2008 mode or better, you can proceed with the migration.
How to Migrate to Office 365
It should be obvious by now the project will be more complex than you expected.
Get your Active Directory in Order
The first step is to take the time to get AD updated and in good working order. Collapse any unwanted domains and forests and update it to at least Windows 2008 mode.
Get rid of legacy systems
Windows XP and Office 2003 must go. The most difficult issue to overcome will be how to upgrade Office before you purchase Office 365. If you buy Office OEM or through volume licensing you are wasting money. If you buy Office 365 months before you start using it, you are wasting money. This is certainly a disincentive to upgrade to Office 365. It would be worth your time to try to negotiate a temporary license for Office to use during the migration.
Migrate to Office 365
The actual migration to Office 365 will be simple compared to the prerequisites. Again, unless you have deep Exchange expertise, hire a consultant. Every situation is a little different and only people that do these migrations regularly can predict how decisions you make will affect you.
I should point out that I am not a consultant … I am the guy that hires the consultants. I am all for saving money but email is important enough to do right.
It might not be this hard
If you stay caught up with technology, are running Windows 7 or better everywhere, have your Active Directory in a mode that was created in the last five years, and avoid 10 year old software, you may be able to migrate with only a little preparation. On the other hand, if you work for a company that only spends money on IT when they have to, the move to Exchange 2012 or Office 365 is going to be very expensive. This is really a good argument for keeping things up to date because in the end … you will have to upgrade everything.