Exchange email coexistence
This allows an on-premise Exchange server (E2k or above) to exist side by side with Exchange Online. It enables you to move users from the on-premise Exchange server to Exchange Online at your own pace over several weeks or even months.

While doing so - users have a mailbox on either system, but retain their original @company.com email addresses and maintain a unified GAL that spans both systems.

Directory synchronization is a prequisite for this.

Directory Synchronization
Setting this up sets an ongoing synchronization from your on-premise Active Directory to Microsoft Online Services. This allows you to master user information in your Active Directory - and only manage license assignment and passwords up in Microsoft Online.

Change someone's Display Name? Do it on-premise and watch it sync up to Microsoft Online. Delete a user in Active Directory? The delete will propogate up to Microsoft Online.

Who needs coexistence?
Typically companies with over a 100 users. The benefits of using coexistence increase directly with the size of the company.

For companies with less than a 100 users, manually managing their users in the Microsoft Online Administraton Center might be acceptable. These companies are also often able to migrate from an on-premise system to Microsoft Online over a weekend, without the need for a phased migration of mail users.

For larger companies, migrating all mail users might take from a few weeks to a few months. Coexistence allows users to be moved across in phases by allowing both systems to work together.

Large companies also find keeping the two user directories in sync (on-premise Active Directory and Microsoft Online) painful, because of the volume of change they are likely to see.

Want to create a "vanity URL" for OWA that looks like https://mail.mycompany.com? Check out the tips on Exchange Online here.

Looking for help getting started with Directory Synchronization? Look at the tips linked to in the column on the left.

I have just made a change in my on-premise Active Directory that I want to sync up to Microsoft Online immediately. Can I force a sync?

DirSync runs and automatically syncs your on-premise Active Directory with Microsoft Online every three hours. To force a sync you have two options

1. Start the DirSync Configuration Wizard and walk through it to the 4th page. You will be asked if you want to start a sync now.
   Doing this requires you to enter your credentials as part of the Configuration Wizard.
   
2. Use the Powershell interface -
   a) Open a Powershell window with the DirSync snapin (if using the default location, double click on C:\Program Files\Microsoft Online Directory Sync\DirSyncConfigShell.psc1).
   b) Run the cmdlet "Start-OnlineCoexistenceSync". This starts a sync using the saved credentials.

You have a few options to accomplish this.

1. Users can sign in to https://home.microsoftonline.com. This URL is simpler and has a link to both OWA and Sharepoint Online sites.
2. The Sign In application presents a link to OWA when open. If Outlook is not installed, the Email and Calendaring link takes you to OWA. If Outlook is installed, clicking on the little arrow on the Email and Calendaring section unhides the link to OWA.
3. Create your own webpage that redirects users to the OWA page.
   
   To create your own redirection site, you will need to create an HTML or ASP file on a web server you own. You can choose to place this at a URL of your selection - eg https://contoso.com/mail or https://mail.contoso.com. It is a nice touch to make your URL work if users type either https:// and https://. The OWA URL will use SSL either way.
   
   Depending on whether you are creating .html or a .asp/.aspx page...
   (Note : replace [REALOWAURL] with the correct OWA URL)
   
   If creating an HTML file, use this example content -
   <HTML>
     <meta http-equiv="refresh" content="0;url=[REALOWAURL]">
     <BODY>
   Loading OWA...
     </BODY>
   </HTML>
   
   If creating an ASP or ASPX file, use this example content -
   <HTML>
     <BODY>
     <%
         Response.Redirect "[REALOWAURL]"
         Response.End
     %>
     </BODY>
   </HTML>
   
   
4. Lastly, if you use a DNS provider like GoDaddy, they might make this easy. GoDaddy allows creating subdomains of a domain that you own and configure forwarding to a different URL easily.
   

Microsoft Online Services (link) are a set of hosted, business class enterprise services that include Exchange Online, Sharepoint Online and CRM Online. A subset of these that focus on communication and collaboration are grouped together as Business Productivity Online (Online versions of Sharepoint, Exchange and Live Meeting).

My blog is focussed on the experiences that allow a customer's on-premise Active Directory (and Exchange) installations to interact with these Business Productivity Online services.

I've just gotten started - so ask questions on this blog and I will answer them as I build out the FAQs! I've long since realized it's easier to come up with answers than it is to ask the right questions. The intent of this blog is help have the right questions heard back within our team - and of course to help get you answers!

I recommend using the following checklist to ease setting up DirSync.

1. Visit the Directory Synchronization tab within the MOAC (Migration - > DirSync) and read the planning documents and enable Directory Synchronization for your company.
   
2. Verify that your technical contact is configured correctly. DirSync error emails are sent to this email address. You can see the technical contact on the lower right hand side page of the MOAC when you sign in.
   
3. Make a list of domains (eg. contoso.com) that your users will need. Verify them from within the Microsoft Online Administration Center (MOAC) if you have not already done so.
   Note : Sub-domains of your domain do not need to be verified, but they do need to be added in the MOAC after you have verified the parent domain. (If you have verified contoso.com, you do need to add sales.contoso.com if you have users@sales.contoso.com. Adding sales.contoso.com does not require verification if contoso.com is verified).
   
4. Find a machine and install DirSync on it. DirSync requires a domain joined machine running Windows 2003 SP2 x86 or Windows 2008 x86 (not a Domain Controller, not x64). The machine does not need to be dedicated to DirSync as long as it is always on. People have sucessfully installed it on a VM.
   
5. Verify DirSync is running correctly.
   Follow steps on MOAC.

DirSync is not a requirement to use Microsoft Online. It is easy to manage small user lists in Microsoft Online using the Administration Portal. You can even import a list of users from a .CSV file.

DirSync makes the most sense when you have large enough user lists that you want to edit information for users only in one place (your Active Directory) and have these changes synchronized with Microsoft Online. Many company's choose to do so only when they have over a 100 users. It is also required if you want to run an on-premise Exchange Server and use Exchange Online at the same time and setup email coexistence.

What is synchronized?

DirSync synchronizes all domains in your Active Directory forest with Microsoft Online. It will synchronize all users, and contacts/groups with email addresses.

Note, these are visible in the Exchange Online Address Book only if they have email addresses.

DirSync does not synchronize privileged information like user passwords from the on-premise Active Directory. Users are assigned a Microsoft Online password when they are licensed.  

What are the prerequisites for Directory Synchronization?

Environment : 

• A single Active Directory Forest (Windows Server 2000 or above DCs)
• Enterprise Administrator Credentials for this forest

DirSync Machine prereqs

• Windows Sever 2003 SP2 x86
• .Net 2.0 Runtime
• Powershell 1.0
• Joined to a domain
• Not a domain controller

Note : If you are testing out the DirSync functionality, it is possible to install it in a Virtual Machine. You will see better performance on Windows 2003 SP2 x86 running within Hyper-V compared to when running within Virtual PC or Server.

Can I roll back after running Directory Synchronization?

DirSync establishes a one way synchronization from the on-premise Active Directory to Microsoft Online. No changes are made to the source AD as part of synchronization.

Changes you will need to make to completely roll back include

1. Uninstall the DirSync Tool.
2. Delete the MSOL_DirSync account created in your AD during the first DirSync Configuration. Help in Configuration Wizard provides details on this service account (used for reading from the source AD).
3. Delete the synchronized objects from Microsoft Online.
4. If mailboxes have been migrated to Microsoft Online, the migration tools present the option to set up mail forwarding to Microsoft Online. You can remove any forwarding you have set up using the Migration Tools.

Does DirSync work with proxy servers?

Yes! DirSync does work with proxy servers. DirSync communicates with Microsoft Online via ports 80 (HTTP) and 443 (SSL). All data transfers are transfered securely over SSL. The client uses the the same proxy settings the user configuring the DirSync client uses.

Note : DirSync works with unauthenticated proxies. If you do have a proxy server that requires authentication, you will have to establish exceptions to allow unauthenticated traffic to *.microsoftonline.com from the DirSync client.

I think objects from my AD are not synchronizing into Microsoft Online!

The following object types are synchronized into Microsoft Online.

1. Users
2. Contacts with email addresses
3. Groups with email addresses