The challenge
A lot of mail, and a business that still had to send it
The client is a Canadian manufacturer. Daily work sat in Google Workspace. Gmail held the mail. Google Drive held the files. The mailboxes were not light. Together they came to about 450 GB of mailbox data, hundreds of gigabytes that had to move with the people who still needed them. Fewer than 20 users were in scope. That is a small directory and a large amount of history.
The company had decided Microsoft 365 was the next home for that mail and those files. The hard part was not the decision. It was getting the data across without treating the cutover as a hope. Large mailboxes take time to sync. DNS has to follow the data, or new mail lands in the system that was just retired. And the days after are when people notice what the sync got wrong. Labels, in particular, are how a mailbox stays usable. A migration that drops them looks finished in the admin console and broken at the desk.
What the client needed was a weekend in which Gmail and Google Drive actually moved, a final sync before DNS changed, and someone still there the next day.
Our approach
BITSUMMIT ran the move from Google Workspace to Microsoft 365 around that sequence, with no long program of optional work: the mail and the files, the cutover, the days after, and the security and governance work that belonged after mail was flowing.
The weekend the data moved
Gmail and Google Drive were cut over in the same weekend window. The final sync ran first, so the history that had accumulated up to the cutover was in the new tenant before DNS was switched. Then DNS was cut over, so mail flow followed the data instead of racing ahead of it.
Fewer than 20 users were in the move. The mailbox data was about 450 GB, and the Drive files went with it. The point of doing both together was simple. A manufacturer that has its mail in one place and its files in another has not finished the move.
The weekend was a scheduled window. It is not a claim that nobody noticed, and it is not a claim that nothing was interrupted. It is when the cutover was done.
The days after
A support bridge ran the next day. That is a different job from the sync. The sync moves bytes. The bridge is where someone answers the mailbox that does not look the way it did before the cutover.
Mailbox labels were the issue that stood out. They had not synced cleanly. Later that week, BITSUMMIT remediated the label sync and set a migration approach for labels, rather than leaving it as a note for later. People search old mail by the labels they already trust. Leaving the labels wrong would have made a completed cutover feel like lost mail, even with the messages sitting in the new tenant.
Security and governance, after mail was across
With the data moved and DNS pointing at the new tenant, BITSUMMIT did the security and governance work that followed the cutover. Post-migration documentation and testing across all users were completed at the same stage. The order is the point. Get the mail and the files across, then do the governance, rather than treating a settings list as the migration.
The outcome
- Mail and files in Microsoft 365. Gmail and Google Drive for fewer than 20 users moved in one weekend, including about 450 GB of mailbox data.
- DNS followed the final sync. Mail flow was switched after the history had been brought across, not before.
- A bridge the next day, and follow-through after it. A support bridge ran the day after cutover, and a mailbox label-sync issue was remediated later that week.
- Governance after the move. Security and governance work, along with documentation and testing across all users, followed once mail was flowing in Microsoft 365.
A migration of this size is easy to describe as a tenant and a licence. The work was the 450 GB, the Drive files, the DNS change, the support bridge, and the follow-up that fixed the labels.
Other organizations have made the same kind of change from a different starting point. See how one team left Google Workspace for Microsoft 365, and how another moved a legacy mail system into Microsoft 365. More on our modern workspace practice.
Still running mail and files in Google Workspace? Book a Microsoft 365 migration review. We'll look at the mailboxes, the files, and the DNS cutover with you, and plan the days after as part of the move.
