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Insights & News How to Migrate Email to Microsoft 365: A Step-by-Step Guide June 10, 2026 To migrate email to Microsoft 365, you set up the new tenant, verify your domain, choose a migration method to match your source (cutover, staged, or a direct import from another cloud provider), copy mailboxes across, then switch your domain’s mail records so new mail flows to Microsoft 365. Done in the right order, staff keep working throughout and no mail is lost. The order matters far more than the tooling. Key facts Email migration to Microsoft 365 has four stages: prepare the tenant, verify the domain, migrate mailboxes, then cut over the mail records. The migration method depends on the source: a cutover for small environments, staged for larger ones, or IMAP/cloud migration from non-Microsoft providers. The domain’s MX record is switched only after mailboxes are migrated, so mail keeps flowing to the old system until the cutover. Shared mailboxes, distribution lists, and calendar permissions are the parts most often forgotten and most likely to cause problems. For Australian tenants, migrated mail is stored at rest in Microsoft’s Australian data centres. How do you migrate email to Microsoft 365? The migration runs in a deliberate sequence. First, prepare the Microsoft 365 tenant: assign licences and create the user accounts. Second, verify your domain in Microsoft 365 so it knows you own it. Third, migrate the mailbox contents from the old system. Fourth, change the domain’s MX record so incoming mail starts arriving at Microsoft 365. Only then do you decommission the old mail system. The reason the MX record change comes last is simple: until mailboxes are copied across, you want new mail still landing in the old system so nothing falls into a gap. Switch the MX too early and mail arrives in an empty mailbox while the migration is still running. Get the order right and the transition is invisible from the user’s side. Which migration method should you use? The right method depends on where your email lives now. A cutover migration moves everyone at once and suits small environments on an existing Exchange server. A staged migration moves users in batches and suits larger or more complex setups. An IMAP or cloud migration is used when coming from a non-Microsoft provider such as Google Workspace or a basic hosting mailbox. Each method has trade-offs around downtime, complexity, and how much history comes across. We pick based on your source system, mailbox count, data volume, and how much disruption you can tolerate. There is no single best method, only the right one for your environment, which is why the audit comes before the choice. What gets missed in an email migration? The mailbox content itself is the easy part. What gets missed is everything around it: shared mailboxes that several people rely on, distribution lists, mail-enabled security groups, calendar sharing permissions, mailbox rules, and email signatures. These do not always migrate automatically, and when they are forgotten, staff notice within hours. The migrations that go wrong are almost always the ones where someone counted user mailboxes and stopped there. A director whose calendar is shared with five assistants, a shared “accounts@” mailbox three people monitor, a distribution list that external partners email: none of these show up in a simple user count, and all of them break loudly if missed. Mapping them up front is the difference between a clean migration and a week of cleanup. We treat this audit as the core of every Microsoft 365 migration. Frequently asked questions Will we lose any old emails in the migration? A properly run migration copies the full mailbox history across and verifies it before the old system is switched off, so no mail is lost. The data is copied, not moved, meaning it exists in both places until the cutover is confirmed complete. The risk of loss comes from rushing the verification step, not from migration itself. How long is email down during a migration? Email should not be down at all. With the cutover scheduled outside business hours and the MX change timed correctly, mail keeps flowing throughout. Staff may need to re-add their account to Outlook and their phone once, but there should be no window where messages bounce or go missing. Can we migrate from Google Workspace to Microsoft 365? Yes. Migrating from Google Workspace is common and uses a cloud migration method suited to non-Microsoft sources. Gmail, Google Calendar, and Contacts move across, though Google-specific features like labels and shared drives need careful handling. We map those quirks during the audit so nothing is lost in translation. Do we need an IT provider, or can we do it ourselves? A small, simple mailbox move is achievable in-house if you are comfortable with DNS and the Microsoft 365 admin centre. The trouble usually comes from the parts that are easy to overlook, the shared mailboxes, permissions, and DNS timing. For most businesses, the cost of a provider doing it cleanly is less than the cost of an afternoon of bounced mail and lost calendar access. If you are planning to move your email to Microsoft 365, the safest first step is a short audit of your mailboxes, shared accounts, and permissions before anyone touches DNS. We are happy to map that out and give you a clear, no-surprises plan. About the author Brett Muscio is the Director of 4iT Support Pty Ltd, a managed services provider based in Castle Hill, NSW. He works with SME clients across Sydney, Melbourne, and Brisbane on Microsoft 365 environments, including email and tenant migrations, mail flow, and conditional access, with on-site support across the Sydney metro area and remote delivery nationally. Connect on LinkedIn. Recent Posts How to Migrate Email to Microsoft 365: A Step-by-Step Guide Microsoft 365 Business Premium vs Business Standard: Which Plan Do You Need? Teams vs SharePoint for File Storage: What Goes Where? OneDrive vs SharePoint: Which One Should Your Business Use? Cyber Security for Small