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If you are planning a phased (batch) migration from Google Workspace to Office 365, setting up split delivery between the source and the destination will make sure you do not skip any email. This email handling technique is popular in mid-size to large enterprises that cannot afford a cutover migration due to downtime issues.
Having done this configuration several times in my own organization, I know where to start from and where to end. Through this blog, I will help you set up split delivery in G Suite without breaking anything.
What is Google Workspace Split Delivery?
Let’s say during a Google Workspace to Office 365 batch migration, you migrated all the mailboxes of the IT department, but the finance and sales department mailboxes are still on Google’s server. Suppose you get two new emails, one is for the IT department, and the other is for finance, but there are no mailboxes of IT in Google. Now, will both the emails go to Google or to Office 365? That’s where the split delivery comes in.
It is a configuration that allows Google to route an inbound email to a mailbox inside Google or to a mailbox outside Google’s server (like Exchange). Google termed this function split delivery, and it is a powerful feature to simplify email delivery during a mailbox batch migration.
Benefits of using Split Delivery in G Suite?
There are multiple reasons why major email providers offer this feature, like:
- Help in Phased Migration: Split email delivery allows the business to complete the batch migration while maintaining the domain-wide communication active.
- Run Test Migration: Some admins use split delivery in G Suite to run a pilot Google Workspace to Office 365 migration to find any future potential downsides.
- Keep Original Domain: You do not have to assign temporary email addresses to forward emails to the mailboxes that are migrated. Google will handle email delivery to the right mailbox.
- Smart Risk Mitigation: In case of a delayed license or a destination server issue, the admin can simply reroute the emails back to the original Google Server until the issue is fixed.
Checklist to Set Up Split Delivery in G Suite
Before we modify the administrative settings in Google Workspace (GWS) or Microsoft 365, confirm these:
- Privileges of Super Admin in Google and Global Administrator in Office 365.
- MX records point to Google, and TXT SPF authorizes both Google and Microsoft.
- Domain added and verified in Microsoft along with provisioned user mailboxes.
- A list of user mailboxes that are migrated and that are not.
- Make sure there is no mailbox that is active in both Google and Microsoft.
Step-by-Step Process to Set Up Google Workspace Split Delivery
Once you have taken care of the above prerequisites, you need to work on 2 major steps to establish the flow of email between both the servers.
Step 1: Configure Google Workspace to Add Office 365 as a Mail Route
Split delivery requires a defined destination server before you can route anything to it. For that:
- Sign in to the Google Admin Console with an administrator account.
- Go to Menu > Apps > Google Workspace > Gmail.
- Click on the Hosts section, click the Add Route button, and create a new route pointing to the Microsoft 365 mail server.
- Come back to Gmail settings and this time select the Routing option (you have to scroll down to find it).
- Click the button Add another route and set the route, apply filters, and click Save.
Step 2: Configuring the Microsoft 365 Server
The above settings will only handle inbound mail arriving at Google. To make sure users on Microsoft 365 can also email users who are still on Gmail, you need to configure Microsoft 365. For that, do this:
- In the Exchange admin center, go to Mail flow > Connectors.
- Create a new connector with these settings:
- Connection from: Office 365
- Connection to: Your organization email server.
- Set the connector to use a smart host, pointing to Google Workspace’s MX record.
- Keep TLS enabled for the connection.
- Go to Mail flow > Accepted domains and make sure the Internal Relay option is selected for the domain.
When to Remove the Split Delivery Rule?
You can delete the Google Workspace split delivery routing rules once the last migration batch is transferred. However, to avoid any issues in email delivery, I suggest you follow this sequence:
- Make changes to the MX records. They must point to the new Microsoft server.
- Wait for 24 to 48 hours, so the changes are propagated.
- Remove the Google record from SPF and update DKIM & DMARC rules.
- Now, remove the routing rules from Google and Microsoft.
- After waiting for a few weeks, decommission the old Google license.
Common Problems When Setting Up Split Delivery in G Suite
These are the issues that you may face during the configuration:
- Mail bounces from Office 365 to Gmail users: Almost always caused by the domain still being set as “Authoritative” instead of “Internal Relay” in Exchange Online, or a missing/misconfigured connector.
- Mail bounces from Gmail to Office 365 users: This issue mainly arises when you missed adding the recipient address in the envelope filter, or the email settings to catch any unrecognized address were not configured correctly.
- Delayed or no email delivery: The changes you made to the routing can take up to 24 hours to fully propagate across all the domains. Therefore, whenever I do this configuration, I do it the day before the weekend.
- Duplicate messages: Mostly happen when your Google and Microsoft accounts are configured with both the split delivery rule and a dual delivery rule. Check the route and other settings.
Do Not Rely on Google Workspace Split Delivery for Long
If your goal is to only move mailboxes, the native method will suffice. But when the migration involves Drive and Chats, manual moving them across platforms will take a considerable amount of time, as you have to manually export these two for each user and then import them to Microsoft. The more time the migration takes, the longer you will be depending on the split delivery in G Suite.
However, using it for a long time will result in higher licensing costs and complex mailbox architecture. Make sure to finish the migration within a specified time limit. Since the native method is time-consuming, a better approach is to use a professional Google Workspace to Microsoft 365 migration tool like Kernel Google Workspace to Office 365. This tool will migrate all your mailboxes and also offer the advantage of migrating Drive and Chat data, missing in native migration method.
Frequently Asked Questions
No, the feature only works on the new emails that were delivered after you activated the split delivery.
When you set up split delivery, each email that is sent to your domain is analyzed, and based on some pre-defined rules, it will be routed to either Google or another platform. On the contrary, in a dual delivery setup, each email is copied to every domain, meaning one copy to Google and one to another connected platform like Microsoft.
No, other email providers like Microsoft also have a similar feature but with different names.
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