Migrate Zimbra to Microsoft 365 using Zimbra Admin Credentials

Migrating email from an IMAP-based system (Zimbra) to Office 365 can streamline an organization’s email management and enhance productivity with Microsoft’s cloud-based tools. This guide provides a clear, step-by-step process to ensure a smooth migration, using only Admin Credentials from the Zimbra Server.

Step 1. Identify the Email Server’s Full Name

To begin, Office 365 requires the full name of the current IMAP email server to initiate the migration.

Step 2. Create a Migration File for Mailboxes

You’ll need to create a CSV file listing the mailboxes you want to migrate. Office 365 supports migrating up to 50,000 mailboxes in a single file (up to 10 MB), allowing you to migrate in batches for convenience.

Access Source Email System:
- Log in to the current email system (e.g., Zimbra, Gmail, or another IMAP-based system).
Open the Microsoft 365 Admin Center:
- Go to https://admin.microsoft.com.
- Navigate to Users > Active Users and note the usernames listed. These will be used in the migration file.
Create the Migration File:
- Create a CSV file with the following columns:

1. Using User credentials

EmailAddress: The full email address of the Microsoft mailbox (e.g., [email protected]).
UserName: The username for the Zimbra mailbox (e.g., user).
Password: The password for the Zimbra mailbox.

2. Using Admin Credentials

· EmailAddress : Microsoft Email

· UserName : #Zimbra Email#Superadmin_prefix#

· Password : SuperAdmin password

Note: Ensure the CSV file is accurate, as errors in email addresses, usernames, or passwords can cause migration failures.

Step 3. Set Up a Migration Endpoint in Office 365

To connect Office 365 to an IMAP email system, you need to create a migration endpoint in the Exchange Admin Center.

Access the Exchange Admin Center:
- Log in to https://admin.exchange.microsoft.com.
Create a Migration Endpoint:
- Navigate to Recipients > Migration > More (ellipsis) > Migration Endpoints.
- Click New to create a new endpoint.
- On the Select the migration endpoint type page, select IMAP.
- On the IMAP migration configuration page, enter the following:
  - IMAP Server: The server name from Step 1 (e.g., imap.domain.com).
  - Authentication: Choose the appropriate method (usually Basic Authentication).
  - Port: Use the default IMAP port (993 for secure connections) unless otherwise specified.
- Click Next.
- On the Enter general information page, provide a Migration Endpoint Name (e.g., IMAP_Endpoint).
- Leave the other fields blank to use default values.
- Click New to create the endpoint.

Note: Ensure the IMAP server supports SSL/TLS for secure migration.

Should enable port 993

Step 4. Create and Run a Migration Batch

With the migration endpoint set up and the CSV file ready, you can now create a migration batch to transfer mailboxes to Office 365.

Navigate to Migration
- In the Exchange Admin Center, go to Recipients > Migration.
- Click New > Migrate to Exchange Online.
Select Migration Type
- Choose IMAP Migration and click Next.
Upload the Migration File
- On the Select the users page, click Browse and select the migration_batch.csv file you created.
- Office 365 will validate the file and display the number of mailboxes to be migrated.
- Click Next.
Configure the Migration:
- On the IMAP migration configuration page, verify the settings and click Next.
- Select the migration endpoint created in Step 3.
Name the Migration Batch:
- On the Move configuration page, enter a batch name (e.g., Test5-migration). Avoid spaces or special characters.
- Click Next.
Start the Migration:
- Review the settings and click New to begin the migration process.
- Monitor the migration status in the Exchange Admin Center under Recipients > Migration.

Step 5. Verify Migration Success

Once the migration is complete, check the status in the Exchange Admin Center.

A Synced status indicates a successful migration for a mailbox.
If errors occur, review the migration logs for details and verify the CSV file or endpoint settings.
Test access to the migrated mailboxes in Office 365 by logging in to https://outlook.office.com with the migrated user credentials.

Note: It is better to use administrator credentials because it doesn't affect or inconvenience users. For example, it won't matter if users change their passwords after the initial migration.