How a GWMME migration works

Google Workspace Migration for Microsoft Exchange

You can migrate your users' email, calendar, and contact data from a Microsoft Exchange server using Google Workspace Migration for Microsoft Exchange (GWMME). If you use an RFC 3501-compliant IMAP server to route mail, such as Novell GroupWise, you can also use GWMME to migrate email to your Google Workspace account.

Exchange migrations

What's migrated?

You can migrate email, calendar, and contact data from Exchange.

Overview of an Exchange migration

GWMME connects to Exchange and uploads the data to Google Workspace using the Gmail API.

How does GWMME retrieve the data from the Exchange server?

When you set up GWMME, you specify the Exchange administrator credentials. You also provide a comma-separated values (CSV) file that specifies the Exchange username and the corresponding Google Workspace username. During a migration, GWMME connects to Exchange and transfers the data to Google Workspace using the information in the CSV file.

GWMME translates the email message from MAPI to MIME (an email protocol) using Microsoft Outlook. Any machine running an Exchange migration must have Outlook installed to implement this process.

Tip: You can use GWMME in a hosted Exchange environment. However, the way you set up your administrator profile is a little different. Learn more

What happens when I run a migration again?

The first time GWMME migrates a message or PST file, it writes a custom property at the root of the message store. After a message is migrated, the same custom property is also written on the message object. If you run another migration, GWMME compares the properties. If they match, GWMME bypasses the message because it’s already been migrated.

If instead you choose to migrate all data, a new property is generated and written to the root of the message store. Since the new property doesn't match the value on an existing message, all messages are migrated, including any previously transferred.

IMAP migrations

What's migrated?

You can only migrate email data from IMAP servers.

Overview of an IMAP migration

GWMME connects to the IMAP server and accesses email using the IMAP protocol. Then, GWMME uploads mail to the Google Workspace mailbox using the Gmail API.

How does GWMME retrieve mail from the IMAP server?

When you set up GWMME, you specify the host name or IP address of your IMAP server. You also provide a CSV file that specifies the usernames you want to migrate. During a migration, GWMME connects to the IMAP server and signs in to the user accounts using the information from the CSV file.

When a message is retrieved, GWMME uploads the message to the Google Workspace mailbox using the Gmail API.

What happens when I run a migration again?

When data is migrated, its migration status is stored locally in a SQLite database. If you run a migration again on the same machine, the database helps GWMME bypass any data previously migrated.

Comparing IMAP and Exchange migrations

If you use GWMME to migrate from an IMAP server, only email messages are migrated. If you migrate from Exchange server, GWMME migrates email, calendar, and contact data.

The other main difference between IMAP and Exchange migrations is the way the servers retrieve data:

  • IMAP migrations connect to source servers and retrieve email data through IMAP.
  • Exchange migrations connect to Exchange servers and use local Outlook functions to retrieve email, calendar, and contact data.

Although IMAP and Exchange migrations retrieve data using different processes, they both upload the data using the Gmail API.

Related topics


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