How to Migrate from an On-Premise MS Exchange Server to Google Apps

by Denise Hazime on October 16, 2013

In the last part of our migration series, we covered the steps to take when migrating from an IMAP server using the Google Apps Migration for MS tool (GAMME). Today we’ll be discussing the process of migrating from an in-house MS Exchange server. The best part of migrating from a MS Exchange server as opposed to migrating using an IMAP server is that GAMME will allow you to migrate emails, contacts and calendar events (Public Calendars require additional steps that we will be covering in depth in a future post). The first thing to remember is to not run GAMME from the MS Exchange server itself as Google does not recommend doing so. It’s best to install the tool on a workstation that is connected to the network that the MS Exchange server is a part of.

You can download GAMME on a Windows workstation that has MS Outlook +2003 installed on it by going to

Once you’ve installed the tool go to the Windows Start button > Google Apps Migration for Microsoft® Exchange to get started. You will need to enter the source MS Exchange server’s settings on the first page; you will need to specify the server name (or IP address) and the MS Exchange administrator’s username which you might get prompted to enter a password for further down the road.

Create a CSV spreadsheet with all the users that you want to migrate. The format should be as follows (no need to add the headers below, this is just an example of the format):

Save the CSV file and upload it on the next page of GAMME: Users and Domain Information under File of Users to Migrate. You will need to enter the Google Apps Domain Name and the Google Apps Two-legged OAuth Consumer Key and Secret. This information can be gathered from your Google Apps admin console, where you need to make sure certain settings are enabled.

You will need to enable API access under Security > API Reference > API Access > Make sure Enable API access is checkmarked.

The Consumer Key is your Google Apps domain name. The Consumer Secret is generated in your Google Apps administrator console under Security > Advanced Settings > Authentication > Manage OAuth Domain Key:

  • OAuth Consumer Key: - Make sure Enable this Consumer Key is checkmarked

  • OAuth Consumer Secret: You can click on Regenerate OAuth Consumer Secret if you run into issues with the previously-generated secret.

Under Advanced Settings you will also need to navigate to Manage Third Party OAuth Client Access and enter the following information:

  • Client Name: Your Consumer Key which is your domain name.

  • One or More API Scopes (copy/paste the following as is):,,,,,,

Then click on Authorize. If created correctly it should look like this:

Now that you’ve completed those steps you can return to GAMME’s next page, Migration Setting, for which you will need to specify which services to migrate: Mail, Contacts and/or Calendar events. You can also make it migrate all emails from a specific date range. You can tell GAMME to skip certain top-level folders from all users’ mailboxes as well as Deleted Items and Junk Mail. If you want to limit the numbers of migrations running at the same time you can limit that by checkmarking the Restrict Migration to [200] Users At A Time.

On the next page, review the settings that you just entered then Save Settings in case you need to run the migration again in the future. We recommend enabling Running Diagnostics, Estimate and Migrate:

Once you’ve successfully run the Diagnostics checks to validate your settings you can then click on Start to begin the Estimation process to find out how many emails will be migrated for all users.

GAMME will let you know how much data needs to be migrated and will log each step it takes which you can review in the Log file and Error Reports in case there are errors you need to resolve.

During the migration we advise the users that they can log in to their Google Apps mailbox to send/receive emails however we recommend that they don’t move migrated emails out of their labels (folders) and that they don’t rename or delete migrated labels until the migration is complete. For more details feel free to review the admin guide and contact us today!

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