Do you want to migrate all your on-premises Exchange mailboxes to Exchange Online in Office 365, but still allow users to use their on-premises username and password to access their new cloud mailboxes and existing on-premises resources? If yes than the solution of your problem is cut over migration from Exchange on-premises to Office 365. If your on-premises organization is running Exchange 2003 or later and you have less than 1000 mailboxes, you can perform a cutover Exchange migration to move all your mailboxes to Office 365. Now to retain the old usernames and password all you have to do is implement a single sign-on (SSO) solution by deploying Active Directory Federation Services 2.0 (AD FS 2.0).
There’s an automated tool available in Office 365 ECP (Exchange Control Panel) you can use to migrate all Mailboxes from your existing Exchange environment to Office 365. This method is referred to as a Cut-over Exchange Migration.
In a Cutover Exchange Migration, the migration tool will:
• Provide all mailboxes in Office 365 according to the information found in the on-premises Exchange environment
• Migrate all messages, contacts and calendar items to Exchange online;
• Synchronize the on-premises Exchange mailboxes with the Exchange Online mailboxes every 24 hours until the switch is made from on-premises Exchange to Exchange Online.
First of all create an Office 365 E3 subscription and accompanying management account. Using this account the .nl SMTP domain is created and validated using the validation tool. After validation, Exchange Online is specified as domain services in the Office 365 Management tool.
To provision all mailboxes, distribution groups and contacts the migration tool can be used. The migration tool uses Outlook Anywhere. For accessing the individual mailboxes a service account is used and this account needs the Full Access (including Receive As) permission on the Mailbox Database where the mailboxes reside. So make sure it has that before you proceed! To start the migration tool logon as the Exchange Online administrator and go to the options pages (Exchange Control Panel). In ECP select “Manage my Organization” and click on “E-mail migration”. Make sure that all the auto discovered connection settings are correct. The service account information needs to be entered along with the Exchange Server and the RPC proxy server.
When you click “Next” the connection to the on-premises Exchange environment is tested. When successful the batch is shown, including the number of mailboxes found in the on-premises environment. When everything is ok, click “Run” to start the migration. The mailboxes, contacts and Distribution Groups will be read from the on-premises environment and will be created in Exchange Online. Once created, the tool will use Outlook Anywhere to log into the various mailboxes and copy all the data from the Exchange mailboxes into the Exchange Online mailboxes. Once the migration run is finished an e-mail is sent from the migration tool with the results of the migration. Lastly to finish the migration. Set MX records, Autodiscover record and SPF record to point to Office 365. This way new SMTP message are no longer delivered to the on-premises environment but to the Office 365 environment. Reconfigure the mail clients to use the Office 365 mailboxes and finalize the exchange migration. This was the “cut-over point”.