Email migration
Also known as: mailbox migration, email system migration, email migrations
Email migration is the process of moving email accounts, including messages, folders, contacts, and calendars, from one email system to another, such as from a web host's email or Google Workspace to Microsoft 365, or between Microsoft 365 tenants after a merger.
It involves copying data, updating DNS records, reconfiguring devices, and helping users through the switch. While migration tools have improved a lot, poor planning can still cause lost messages, broken calendar invites, and confused staff.
Email migration, explained at three levels
At home
Email migration is like moving house. You pack years of belongings, move them to the new place, then file a change of address so new mail arrives there. With email, software copies your messages, folders, contacts and calendars to the new service, then a DNS change redirects incoming mail, and a final sweep picks up anything delivered during the move.
At work
Email migration moves a company's mailboxes, including messages, calendars, contacts and shared mailboxes, from one system to another, such as from a web host to Microsoft 365. Data is copied in the background, then DNS records switch new mail to the new service. Businesses care because a well-planned migration avoids lost messages and downtime, while a rushed one confuses staff and customers.
At home
Email migration copies years of messages, folders, contacts and calendars from one system to another, then redirects new mail to the new one. Tools sign in to both systems and copy everything in the background over days, while people keep using the old system. At cutover, the domain's MX records change so new mail arrives at the new provider. A final sync copies anything that arrived during the switch, and devices are reconfigured to connect to the new service.
At work
Migrations usually pre-stage data with tools such as Microsoft's migration service or third-party tools like BitTitan MigrationWiz, cut over by updating MX records, then run a final delta sync. Afterward, Outlook profiles and phones are reconfigured, and shared mailboxes, delegate permissions, distribution lists, forwarding rules and calendar sharing are checked, since these often do not migrate cleanly. Autodiscover DNS records direct clients to the new service automatically.
At home
Old email accounts from internet providers or previous services are often deleted soon after you cancel, sometimes with only short notice. Years of messages, receipts and contacts disappear with them, and some services also stop allowing exports after cancellation. Changing your address also means updating it with banks and other accounts. In my view, export everything and confirm the copy opens before closing an old account.
At work
Inventory mailboxes, sizes, shared mailboxes, archives and dependencies such as scanners, applications and devices that send email through the old system. Plan DNS changes, including SPF, DKIM, DMARC and autodiscover, and communicate timelines clearly. Provide day-one support for reconfiguration and missing items. Keep the source system available, read-only if possible, until the migration is verified, and preserve data subject to retention or legal hold requirements.
Real-world examples
At home
Lena's internet provider was shutting down its email service. She exported her messages and contacts and imported them into a new Outlook.com account.
At work
Marcus's Winnipeg MSP migrated a 30-person firm from a web host's email to Microsoft 365. A weekend cutover and a Monday morning help desk kept everyone working.
Common confusions
- Email migration only involves copying messages. — Calendars, contacts, shared mailboxes, permissions, DNS, and devices all need attention.
- Changing the MX record finishes the migration. — A final sync, device reconfiguration, and user support usually follow, and some issues surface days later.
For analysts
I'd inventory everything that sends email, such as printers, scanners, and apps, before migrating. They're the most common things forgotten during cutover.
History & origin
Businesses ran their own email servers, such as Microsoft Exchange and Lotus Notes, through the 1990s and 2000s. The rise of hosted email, with Google Apps in 2006 and Office 365 in 2011, triggered waves of migrations to the cloud. Microsoft and Google built native migration tools, while third-party services handled more complex moves. Mergers and divestitures created demand for tenant-to-tenant migrations, and Microsoft added cross-tenant mailbox migration features in the early 2020s. Microsoft ended support for Exchange Server 2016 and 2019 in October 2025, prompting more organizations to move remaining on-premises mailboxes to the cloud or newer versions. In my view, email migrations succeed or fail on communication more than technology.