Office 365 & Microsoft 365 migration
Office 365 migrations, with history and permissions intact.
Most Office 365 and Microsoft 365 migrations go wrong in the same few places: shared mailbox permissions, calendar delegation and the distribution lists nobody documented. Those get mapped before anything moves, which is why the cutover is boring.
What it costs
Migrations are quoted fixed-price after a free assessment — hourly billing on a migration puts the risk of the unexpected on you. Ongoing support afterwards sits in the $650/month retainer, or ad-hoc at $185/hr scheduled and $145/hr remote.
What actually breaks
The mail itself is the easy part. Modern migration tooling moves mailboxes and their history reliably, and has done for years. What breaks is everything attached to the mailboxes that nobody wrote down.
Shared mailbox permissions. Who has Full Access, who has Send As, who has Send on Behalf — three different things that behave differently, and a reception mailbox that five people relied on silently stops working for four of them.
Calendar delegation. An assistant who has managed a director’s calendar for six years discovers on Monday morning that they cannot see it. This one generates the angriest phone call of any migration.
Distribution lists and mail flow rules. Lists that were edited by three different people over a decade, plus forwarding rules nobody remembers creating that quietly route copies of invoices somewhere.
The cutover
Migrations run in stages with the old system live throughout. Mailbox content is seeded in advance over days, so the actual switch is a short DNS change and a final delta sync rather than a weekend of copying.
That switch happens on an evening or at a weekend. Downtown that is the normal pattern here rather than an out-of-hours premium — a Loop office is empty at 7pm and full at 9am, and a mail cutover belongs in the gap.
The old environment stays reachable until the new one is verified. Rollback is a DNS change, not a rebuild.
What gets forgotten
A migration quote that only counts mailboxes is a quote that will grow. The work that gets missed sits around the edges: OneDrive and SharePoint permissions, Teams membership, shared calendars, mail-enabled security groups, connectors to line-of-business applications that send mail, and the PST files sitting on half a dozen desktops holding the only copy of somebody’s 2019 correspondence.
Device re-enrolment is the other one. Every phone and laptop has to reauthenticate, and if multi-factor is being introduced at the same time — which is usually the right moment — that is a scheduled, supported step rather than something staff work out from an email.
Where you are migrating from
On-premise Exchange. The common case, and usually a server that is out of support or about to be. Hybrid is available where the timing genuinely needs it, but for most businesses under a hundred people a clean cutover is simpler and finishes.
Google Workspace. A different job. Mail and Drive move, but Google Docs formats convert rather than transfer, shared drive permissions map imperfectly, and anything built on Apps Script does not come with you. Worth knowing before you commit, not after.
Tenant to tenant. Acquisitions and splits. The hardest of the three, because two live environments have to keep working while addresses, groups and identities are reconciled.
The day after
Microsoft runs the service. Microsoft does not back up your data for you — retention in 365 is short and is designed for accidental deletion, not for ransomware or a departing employee who cleared their mailbox. Third-party 365 backup is inexpensive and is part of a migration finishing properly, not an upsell after it.
Everything that was mapped during the migration — permissions, groups, delegation, mail flow — is left with you as documentation. For a good number of businesses it is the first written record of how their mail actually works.
FAQ
Questions we get asked
Is Office 365 the same as Microsoft 365?
For business purposes, yes. Microsoft renamed most Office 365 business plans to Microsoft 365 in 2020. It is the same email, Teams, OneDrive and SharePoint service, so an Office 365 migration and a Microsoft 365 migration are the same job.
How long does a Microsoft 365 migration take?
For most businesses under a hundred mailboxes, one to three weeks end to end: assessment, mapping, seeding content in the background, then a cutover measured in hours. Mailbox count matters less than how tangled the permissions are.
Will we lose email history?
No. Mailboxes migrate with full history, folder structure and attachments. PST files found on desktops are imported too, which frequently recovers mail nobody realised was only in one place.
What do staff have to do?
Sign in again, and reauthenticate on their phones. They get a single page describing what changed before the cutover rather than discovering it on Monday. Outlook profiles are rebuilt as part of the work, not left as an exercise.
What happens to shared mailboxes and calendar delegation?
They are mapped before anything moves and verified after. This is the part most migrations get wrong — Full Access, Send As and Send on Behalf are three separate permissions and they do not all carry across by default.
Does Microsoft back up Microsoft 365?
Not in the way people assume. Retention windows are short and aimed at accidental deletion. Ransomware and deliberate deletion are your responsibility, which is why third-party 365 backup is worth having — see backup and recovery.
Can you migrate from Google Workspace?
Yes. Mail, contacts, calendars and Drive move. Native Google Docs convert to Office formats rather than transferring, and anything built on Apps Script will not come across — that gets identified during the assessment so it is a decision rather than a discovery.
Can you take over a migration somebody else started?
Yes, and it happens. It gets assessed first so the current state is actually known, and anything urgent is flagged before agreeing how to finish it.
Ready when you are.
Ring and describe it in plain English. You will get a number before anyone drives anywhere.