You can use the setup wizard in the Microsoft 365 admin center for an IMAP migration. See IMAP migration in the Microsoft 365 admin center for instructions.
Description:
IMAP migration will only migrate emails, not calendar, and contact information. Users can import their own email, contacts, and other mailbox information to Microsoft 365 or Office 365. See Migrate email and contacts to Microsoft 365 to learn how.
Prerequisites:
Before Microsoft 365 or Office 365 can connect to Gmail or Google Workspace, all account owners must create an app password to access their account. This is because Google considers Outlook to be a less secure app and will not allow a connection to it with a password alone. For instructions, see Prepare your Google Workspace account for connecting to Outlook and Microsoft 365 or Office 365. You'll also need to make sure your Google Workspace users can turn on 2-step verification.
Procedures:
In this task, you'll first verify to Microsoft 365 or Office 365 that you own the domain you used for your Google Workspace accounts.
Note
Another option is to use the your company name.onmicrosoft.com domain that is included with your Microsoft 365 or Office 365 subscription instead of using your own custom domain. In that case, you can just add users as described in Add users individually or in bulk and omit this task. Most people, however, prefer to use their own domain.
Domain verification is a task you will go through as you set up Microsoft 365 or Office 365. During setup, the setup wizard provides you with a TXT record you will add at your domain host provider. See Add a domain to Microsoft 365 for the steps to complete in Microsoft 365 admin center, and choose a domain registrar from the two following options to see how to complete add the TXT record that your DNS host provider.
You can add your users either one at a time, or several users at a time. When you add users, you also add licenses to them. Each user has to have a mailbox on Microsoft 365 or Office 365 before you can migrate email to it. Each user also needs a license that includes an Exchange Online plan to use his or her mailbox.
Important
At this point you have verified that you own the domain and created your Google Workspace users and mailboxes in Microsoft 365 or Office 365 with your custom domain. Close the wizard at this step. Do not proceed to Set up domain, until your Gmail mailboxes are migrated to Microsoft 365 or Office 365. You'll finish the setup steps in task 7, Step 6: Update your DNS records to route Gmail directly to Microsoft 365 or Office 365.
For this task, you create a migration file that contains a list of Gmail mailboxes to migrate to Microsoft 365 or Office 365. The easiest way to create the migration file is by using Excel, so we use Excel in these instructions. You can use Excel 2013, Excel 2010, or Excel 2007.
When you create the migration file, you need to know the app password of each Gmail mailbox that you want to migrate. We're assuming you don't know the user passwords, so you'll probably need to assign temporary passwords (by resetting the passwords) to all mailboxes during the migration. You must be an administrator in Google Workspace to reset passwords.
You don't have to migrate all Gmail mailboxes at once. You can do them in batches at your convenience. You can include up to 50,000 mailboxes (one row for each user) in your migration file. The file can be as large as 10 MB.
To migrate Gmail mailboxes successfully, Microsoft 365 or Office 365 needs to connect and communicate with Gmail. To do this, Microsoft 365 or Office 365 uses a migration endpoint. Migration endpoint is a technical term that describes the settings that are used to create the connection so you can migrate the mailboxes. Do the following to create the migration endpoint in Classic Exchange admin center.
Note
For new EAC, the Migration endpoints can be created during the creation of a new migration batch.
You use a migration batch to migrate groups of Gmail mailboxes to Microsoft 365 or Office 365 at the same time. The batch consists of the Gmail mailboxes that you listed in the migration file in the previous Step 4: Connect Microsoft 365 or Office 365 to Gmail.
Note
IMAP migration is not available for new EAC.
Tip
It's a good idea to create a test migration batch with a small number of mailboxes to first test the process. > Use migration files with the same number of rows and, run the batches at similar times during the day. Then compare the total running time for each test batch. This helps you estimate how long it could take to migrate all your mailboxes, how large each migration batch should be, and how many simultaneous connections to the source email system you should use to balance migration speed and internet bandwidth.
If any one of these checks fails, you'll get an error that describes the reason for the failure. If you get an error, you must fix the migration file and resubmit it to create a migration batch.
Note
If you have large user mailboxes and the status shows Syncing for a long time, you may be experiencing bandwidth limits set by Google. For more information, see Bandwidth limits and Sync limits. You can try to unlock the Gmail user or use alternative method to migrate the users. For more information, see Use network upload to import your organization PST files to Microsoft 365 or Office 365 and Third-party tools for Microsoft 365 or Office 365 migrations.
Although this task is optional, doing it can help avoid delays in the receiving email in the new Microsoft 365 or Office 365 mailboxes.
When people outside of your organization send you email, their email systems don't double-check where to send that email every time. Instead, their systems save the location of your email system based on a setting in your DNS server known as a time-to-live (TTL). If you change the location of your email system before the TTL expires, the sender's email system tries to send email to the old location before figuring out that the location changed. This can result in a mail delivery delay. One way to avoid this is to lower the TTL that your DNS server gives to servers outside of your organization. This will make the other organizations refresh the location of your email system more often.
Most email systems ask for an update each hour if a short interval such as 3,600 seconds (one hour) is set. We recommend that you set the interval at least this low before you start the email migration. This setting allows all the systems that send you email enough time to process the change. Then, when you make the final switch over to Microsoft 365 or Office 365, you can change the TTL back to a longer interval.
The place to change the TTL setting is on your email system's mail exchanger record, also called an MX record. This lives in your public facing DNS. If you have more than one MX record, you need to change the value on each record to 3,600 seconds or less.
Don't worry if you skip this task. It might take longer for email to start showing up in your new Microsoft 365 or Office 365 mailboxes, but it will get there.
If you need some help configuring your DNS settings, see Add DNS records to connect your domain.
Email systems use a DNS record called an MX record to figure out where to deliver email. During the email migration process, your MX record was pointing to your Gmail system. Now that you've completed your email migration to Microsoft 365 or Office 365, it's time to point your MX record to Microsoft 365 or Office 365. After you change your MX record following these steps, email sent to users at your custom domain is delivered to Microsoft 365 or Office 365 mailboxes
For many DNS providers, there are specific instructions to change your MX record, see Add DNS records to connect your domain for instructions. If your DNS provider isn't included, or if you want to get a sense of the general directions, general MX record instructions are provided as well. See Add DNS records to connect your domain for instructions.
It can take up to 72 hours for the email systems of your customers and partners to recognize the changed MX record. Wait at least 72 hours before you proceed to stopping synchronization with Gmail.
During the last task, you updated the MX record for your domain. Now it's time to verify that all email is being routed to Microsoft 365 or Office 365. After verification, you can delete the migration batch and stop the synchronization between Gmail and Microsoft 365 or Office 365. Before you take this step:
When you delete the migration batch, the migration service cleans up any records related to the migration batch and removes it from the migration dashboard.
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