Migrating a G-Suite Mailbox to an Office 365 Mailbox: The Easy Way

Our team has been planning for months to open up Vacation Tracker to companies using Microsoft Teams. So we felt it was logical for us to start using Microsoft Teams and Office 365 so we can get more familiar with some of their features, strengths, and weaknesses. We plan to continue using Slack in our parent company Cloud Horizon, but Vacation Tracker will now be fully transferring to Microsoft Teams.

As part of this migration to Teams, we also needed to move our G-Suite mailboxes to Outlook inside Office 365. We spent quite a bit of time trying to find the best method and landed on many overly complex or poorly written articles that did not explain this process well. It’s actually not very difficult at all if you have the correct instructions. And you do not need any external tools to do it, you can get this migration done just with G-Suite and the Office 365 admin center.

In this tutorial, we’ll be talking about the IMAP method of migrating your entire mailbox from G-Suite to Outlook. Please note that you need to be an administrator of both your G-Suite and Office 365 accounts in order to be able to follow the instructions in this article.

So, without further ado, let’s dive right into it.

Getting your G-Suite account ready

Step 1: Activate IMAP

The first order of business is to get your G-Suite account prepared for this migration. You’ll need to generate an “app password” which you will use to import all the mails into Office 365. But before that, you’ll need to make sure IMAP is activated for your G-mail or G-Suite account. To do that:

1. Sign in to your Gmail/G Suite account.
2. Click the gear icon located at the top right of the screen.
3. In the drop-down menu, click Settings.
4. Go to the Forwarding and POP/IMAP tab.
5. Scroll down to IMAP access, and make sure that Enable IMAP is selected.
6. Once this is set, scroll to the bottom and click Save Changes.

Step 2: Activate 2-step verification

After you’ve activated IMAP, you’ll need to enable your Google account to be connected to Office 365. To do that, you need to generate an app password which requires that you activate 2-step verification on your account (thank you Google for adding this extra step!). To do that:

1. Sign in to your account.
2. Select Google apps > Account.
   
3. On the Account page choose Security in the sidebar on the left side of the screen.
4. Under the Signing in with Google, choose the arrow next to the 2-Step verification, and provide your password if asked.
   
5. On the Protect your account with a 2-Step Verification page, choose Get Started.
6. Re-enter your password if asked, and in the Let’s set up your phone step, enter or verify your cell phone. On the next step enter the verification number sent to your cell phone and choose Next.
7. Once the code has been verified by Google you will get to the It worked! Turn on 2-Step Verification? step, click Turn On.

You have several options for how to activate 2-step verification. For simplicity, we chose to do it using a text message but you can choose any of the other alternatives provided by Google. The important thing is to activate 2-step verification so that you can generate the application password needed to import data into Office 365.

Step 3: Create an application password

Which brings us to the final step in Google: creating an application password. To do that:

1. Sign in to your account.
2. Select Google apps > Account.
3. On the Account page choose Security in the sidebar on the left side of the screen.
4. Under the Signing in with Google, choose the arrow next to the App passwords, and provide your password if asked.
5. On the App passwords page, in the Select app drop-down choose Other (custom name).
6. Type in a name, for example, Office 365, and then click GENERATE.

Take note of the app password under Your app password for your device. You will be using this password in the Office 365 admin center.

Please note: The 16-character app password is displayed with spaces so it is easier to read (I blurred the last 12 digits in this screenshot for security reasons) but when you enter it into Office 365, ignore the spaces and enter it as an unbroken string of 16 characters.

This is all that needs to be done on the Google side, now let’s take a look at the Office 365 part.

Migrating to Office 365

With your application password in hand, here are the steps you’ll need to follow in Office 365 to import your G-Suite or Gmail inbox:

1. Sign in to the Microsoft Office 365 admin center.
2. Once logged in, click on the Admin icon.
3. In the sidebar menu, click on Setup and then Data migration.
4. The next step is where many of the instructions we found online fell short. You need to select the data service from which you want to import. Now, if your emails are with gmail.com, click on Gmail (identified in box 1 on the screenshot below). If you are using G-Suite (i.e. you have your own domain name in your email addresses like we do @vacationtracker.io) you need to click on Other email sources (identified in box 2 on the screenshot below).
5. I will assume that you use your own domain in your email addresses so once you click on Other email sources, you will see the following screen.
   You need to enter imap.gmail.com as the IMAP server name, the port should be 993 and security should be set to SSL. After that, enter the email address that you want to migrate (don’t worry you’ll be able to do batches of emails after this screen) and the password for that email account. On this screen, make sure to enter the actual password of the email account, not the password we generated for the application in G-Suite (that 16-digit password will be used in the next step). Once you’ve filled in the selected data service, click on Save.
6. The next screen will display all the users you’ve created in Office 365, and you will be able to batch import all their email inboxes from this screen. For the purposes of these instructions though, I’m just going to import only 1 email address because I only generated 1 application password. So, in the Source email column, enter the email address from which you want to import, and then in the Password column, make sure to enter the 16-digit application password you generated in your Google account. Microsoft will then connect to your G-Suite account and will display Connection successful in the Status column once this is complete.
7. The final step is to click Start migration at the top of the screen.

Microsoft will then being the migration process. Once the process is started, the Microsoft 365 admin center will show a message at the top saying “Your migration is in progress. You can navigate away in the meantime. If the migration slows down your network bandwidth, you may want to stop the migration.” As the migration is happening, the statuses in the Status column should change in the following sequence:

Starting > Validating > Syncing > Synced

This is it, you’re done! Your mailbox has now been migrated from G-Suite to Outlook.

Lav Crnobrnja

The CEO, and co-founder of Vacation Tracker. As the team’s go-to-guy, he loves sharing his knowledge on all things business-related. Can often be found reading books on business success at his countryside cabin.