How to Seamlessly Import Emails from Any IMAP Server to Google Workspace

Switching to Google Workspace often feels like a fresh start — until you remember the years of emails sitting in your old inbox. For businesses, losing access to past conversations, client correspondence, or project history is simply not an option.

Google’s new data migration service changes that. With just a few clicks, Google Workspace admins can now import past emails from virtually any IMAP-based email provider — including Hostinger, Zoho, Yahoo!, iCloud, and many others — directly during the Workspace setup process. The migration runs quietly in the background while you continue configuring your new account, consolidating your important emails into one secure location without the usual headaches.

This guide walks you through everything you need to know: how the migration works, what data can be transferred, the requirements you must meet beforehand, and how to avoid common pitfalls along the way.

What Is IMAP Email Migration?

IMAP (Internet Message Access Protocol) is a standard method that email clients and servers use to access and manage messages stored on a remote server. Most email providers — from webmail services to cPanel-based hosting accounts — support IMAP, which means your emails live on a server rather than only on your local device.

IMAP migration is the process of copying those server-stored emails from your old provider into a new email system. In the context of Google Workspace, it means transferring your existing mailbox contents — messages, folders, attachments, and read/unread status — into Gmail, where they become part of your new Workspace account.

Unlike forwarding, which only captures new incoming messages going forward, IMAP migration preserves your historical email data. That distinction matters for businesses that rely on archived communications for compliance, customer service, or institutional knowledge.

Why Migrate Your Emails to Google Workspace?

There are several practical reasons organizations choose to bring their old emails into Google Workspace rather than leaving them behind:

Consolidation. Managing multiple email accounts across different platforms creates friction. Importing past emails into Google Workspace puts everything in one place, searchable and accessible from any device.

Business continuity. Client conversations, contract discussions, and project histories often live in email. Losing that archive during a platform switch can disrupt operations and damage relationships.

Compliance and records. Many industries require organizations to retain email records for specific periods. A proper migration ensures those records remain available and auditable.

Search and productivity. Gmail’s search capabilities — powered by Google’s indexing — make finding old messages far easier than digging through folders on a legacy IMAP server.

Reduced dependency on legacy systems. Once emails are migrated, you can decommission old email servers, reducing maintenance costs and security exposure.

How IMAP Migration to Google Workspace Works

Google’s new data migration service operates through the Google Admin console. The process connects to your source IMAP server, authenticates using the credentials you provide, and then copies email data into the corresponding Google Workspace user accounts.

Here is the basic flow:

1. You provide connection details. This includes the IMAP server address (e.g., imap.example.com), along with the email address and password for each user being migrated.

2. Google connects to the source server. The service tests the connection and establishes a secure link.

3. Data is copied in the background. Emails, folders, and attachments transfer to Gmail. The migration service uses TLS encryption for the connection, and your source server must have a trusted TLS certificate.

4. You map users. A migration map connects each source email address to the corresponding Google Workspace account.

5. The migration completes and you verify. After the transfer finishes, you check that the data appears correctly in Gmail.

The entire process runs while you continue setting up Workspace, so you are not blocked from configuring other aspects of your account. Google notes that the data import process runs in the background once you have completed domain verification and email activation.

What Data Can Be Migrated (and What Cannot)

Understanding what the migration service can and cannot transfer helps set realistic expectations. Here is a summary based on Google’s documentation:

The migration service handles email and label data only. If you need to move calendars, contacts, or files, those require separate migration steps or tools.

Key Requirements Before You Begin

Before starting the migration, several prerequisites must be in place. Missing any of these is a common cause of failed or delayed migrations.

• Super administrator access. Only a super administrator can set up and run the migration from the Google Admin console. Resellers cannot perform migrations on behalf of their customers.

• Verified domain and activated email. You must complete domain verification and email activation before importing users and data.

• User accounts created. The migration service copies data only into existing Google Workspace user accounts. It does not create new accounts from the migrated data.

• Gmail service enabled. Gmail must be turned on for the users you are migrating.

• User licenses assigned. Each migrating user needs an active license before they can use Google services.

• TLS certificate on the source server. If you are migrating from an IMAP server (not Gmail or Google Workspace), your source server must have a TLS certificate signed by a trusted third-party certificate authority.

• Google IP addresses accessible. Your source server must be able to connect to Google’s IP address ranges.

Additionally, if the user account belongs to an organization, IMAP must be turned on at the organization level in the target account.

Step-by-Step: How to Migrate Emails from IMAP to Google Workspace

The following steps describe the migration process using the new data migration service in the Google Admin console.

 1: Sign In and Navigate to Migration

Sign in to the Google Admin console using a super administrator account. Navigate to Data → Data import & export → Data migration. Select IMAP as the migration type.

 2: Connect to Your IMAP Server

Enter the IMAP server address. For example, if your provider is Hostinger, you would enter imap.hostinger.com. Google provides a reference table for common providers, including:

• iCloud: imap.mail.me.com

• Yahoo!: imap.mail.yahoo.com

• Zoho (personal): imap.zoho.com

• Zoho (organization): imappro.zoho.com

• Microsoft 365 / Outlook: outlook.office365.com

Click Test connection. A successful connection shows a confirmation message.

 3: Prepare and Upload the Migration Map

Create a CSV file that maps each source IMAP email address to the corresponding Google Workspace address. The file must include:

• The IMAP email address

• The IMAP password

• The Google Workspace email address

You can migrate up to 100 IMAP users at a time. Each source user maps to a single Workspace user — the service does not support migrating one IMAP user to multiple Workspace accounts.

 4: Start the Migration

Upload the CSV file and begin the migration. The service connects to each source mailbox and copies the email data to the corresponding Workspace account. The migration runs in the background, so you can continue with other setup tasks.

 5: Monitor Progress

The Admin console shows the status of each user’s migration. For large mailboxes, the process may take multiple days due to Google’s daily IMAP download limits (discussed in the next section).

Common Challenges and How to Handle Them

IMAP Throttling Limits

Google enforces daily limits on IMAP data transfer. The current limit is approximately 2,500 MB (2.5 GB) downloaded per day per account. If a migration exceeds this limit, Google may temporarily throttle or restrict access to the account for up to 24 hours.

For context:

• Small mailboxes (under 2.5 GB) typically complete in a single day

• Medium mailboxes (2.5–10 GB) may take 2–3 days

• Large mailboxes (over 10 GB) may require 3 or more days

What to do: Plan migrations during periods when users can tolerate a multi-day window. Avoid running migrations for many large mailboxes simultaneously if you want to reduce the risk of hitting account-level restrictions.

Authentication Issues

Some IMAP providers require app-specific passwords, especially when two-factor authentication is enabled. If the migration service cannot authenticate, check whether your provider requires an app password instead of the regular account password.

TLS Certificate Problems

If your source server does not have a trusted TLS certificate — common with internal or self-hosted mail servers — the migration service may not connect. In that case, you may need to use Google Workspace Migrate (a separate tool) or resolve the certificate issue first.

Large Attachments

Attachments that push a message over 25 MB in total size, or that are on Gmail’s blocked file type list, will not transfer. Users should be informed that some historical attachments may not appear.

Folders Not Mapping Correctly

IMAP folders transfer to Gmail as labels. If your source server uses nested folders, they should map to nested labels, but unusual folder structures or special-use folders (like “Sent Items” with non-standard names) can sometimes require manual review after migration.

Reducing Downtime and Preventing Data Loss

The migration service is designed to run alongside your normal operations, but a few strategies can help minimize disruption:

Run the migration before changing MX records. Keep your existing email provider active while the migration copies historical data. Only switch your domain’s MX records to Google after the migration completes. This ensures that no incoming messages are lost during the transition.

Migrate in phases for large organizations. Rather than migrating all users at once, group users by department or mailbox size. This reduces the load on both the source server and Google’s migration infrastructure.

Do a final delta sync. If your email provider supports it, run a second migration pass after the initial bulk transfer to capture any messages that arrived during the migration window. Google’s data migration service supports delta migrations, which copy only new data since the last pass.

Communicate with users. Let users know that during migration their old emails may not be immediately visible in Gmail. Once the process completes, all migrated messages will appear.

Security and Privacy Considerations

Email migration involves transferring sensitive business communications. A few security points deserve attention:

TLS encryption. The data migration service communicates over TLS. Your source IMAP server must have a certificate signed by a trusted certificate authority. This protects data in transit between the source server and Google.

Credential handling. The migration map CSV file contains user passwords for the source server. Store this file securely and delete it after the migration is complete. Consider using app-specific passwords where possible, so you do not expose primary account credentials.

Access control. Only super administrators can initiate and manage migrations. Ensure that admin accounts are protected with strong authentication.

Data residency. Google Workspace stores data in Google’s infrastructure. Organizations with specific data residency requirements should review Google’s data processing terms before migration.

Post-migration password changes. After the migration, users should change their Google Workspace passwords if there is any concern about credential exposure during the migration process.

Post-Migration Verification Checklist

Once the migration completes, verify the following before decommissioning your old email system:

• Message count. Compare the number of messages in key folders on the source server with the corresponding Gmail labels.

• Folder/label mapping. Confirm that folder structures appear correctly as Gmail labels.

• Attachment integrity. Spot-check messages with attachments to ensure they open properly.

• Read/unread status. Verify that read and unread indicators are preserved.

• Search functionality. Test Gmail search for specific senders, dates, or keywords from the migrated data.

• Recent messages. Check that the most recent messages (from the final days of the migration) are present.

• User confirmation. Ask a sample of users to confirm that their historical emails appear as expected.

Best Practices for Organizations

Plan the migration during a low-activity period. While the migration runs in the background, large transfers can temporarily affect source server performance.

Create user accounts before starting. The migration service requires existing Workspace accounts. Create and license all users first.

Use the CSV template carefully. Incorrect email addresses or passwords in the migration map are the most common cause of failed user migrations. Validate the file before uploading.

Migrate in batches of 100 or fewer. The service supports up to 100 IMAP users per migration batch. For larger organizations, plan multiple batches.

Keep the source server running until verification is complete. Do not cancel your old email hosting until you have confirmed that all data is present in Google Workspace.

Document the process. Record server addresses, migration dates, and any issues encountered. This documentation helps with future migrations or audits.

Conclusion

Importing past emails from an IMAP server to Google Workspace no longer requires complex third-party tools or days of manual configuration. With Google’s data migration service, admins can connect to virtually any IMAP provider and transfer historical email data directly into Workspace — all while continuing with the rest of the setup process.

The key to a smooth migration is preparation: create user accounts, verify your domain, enable Gmail, and ensure your source server has a valid TLS certificate. Once the migration is running, patience matters — especially for large mailboxes that may take several days to transfer due to Google’s daily IMAP limits.