Discovery decides everything else
Mailbox count and sizes, shared mailboxes, distribution lists, calendars, public folders, old archives and the applications that send email all change the method and the timescale.
Email, files and identities · planned and run for you
Microsoft 365 Migration for UK Businesses
Moving email and files to Microsoft 365 is mostly a planning job. The technical steps are well understood; what goes wrong is scope nobody checked, a mailbox size nobody measured, a shared calendar nobody mentioned and a DNS change made at the wrong hour. We do the discovery first, migrate in a pilot before the main run, and keep mail flowing throughout.
- From Exchange, an IMAP host, Google Workspace or another tenant
- Mailboxes, shared mailboxes, calendars, contacts and files
- Piloted with real users before anyone else moves
- Support for the fortnight after, when the questions arrive
Mail keeps flowing while the migration runs. The cutover is scheduled for a quiet window and agreed with you in advance. We will not promise a date before seeing what is being moved.
Direct answer
What is a Microsoft 365 migration service?
A Microsoft 365 migration service plans and carries out the move of your email, calendars, contacts and files into Microsoft 365, and supports the business through the change. The work is discovery, choosing the migration method that suits what you are moving from, a pilot with real users, the cutover itself, then the fortnight afterwards when the practical questions appear.
A pilot before the main run
Moving a small group of real users first finds the problems that no inventory shows: a mail rule nobody documented, a scanner that sends by SMTP, a shared calendar three teams rely on.
Mail keeps flowing
Email is not switched off while the migration runs. The DNS cutover is the brief moment that matters, and it is scheduled for a quiet window rather than mid-morning on a Monday.
The fortnight after is part of the job
Most support demand lands after go-live: signatures, mobile devices, a missing shared mailbox, a permission that did not carry over. Treating that as part of the project is the difference between a smooth move and a bad one.
Where you are moving from
The starting point changes the method
"Migrate to Microsoft 365" covers several quite different jobs. What you are moving from decides which tools apply, how long it takes and how much can run in the background before any cutover.
On-premises Exchange
A server in the office or a data centre. The most tool-supported route, and the one where a hybrid arrangement can let mailboxes move in batches while both systems coexist.
Usually involves: directory sync, a cutover or staged batch plan, decommissioning the old server once nothing depends on it.
A POP or IMAP mail host
Typical of small businesses on a web host's mail package. Mail content moves by IMAP; calendars and contacts usually do not come across on their own and have to be handled separately.
Watch for: mail that exists only in Outlook on one PC, no central copy, and the webmail account nobody has the password for.
Google Workspace
Mail, Drive, calendars and contacts move, but the collaboration habits do not translate one to one. Shared Drives, Google Docs formats and sharing links all need a decision rather than a straight copy.
Decide first: what becomes SharePoint, what becomes OneDrive, and which documents convert rather than sit in Drive format.
Another Microsoft 365 tenant
Common after an acquisition, a demerger or a rushed setup by a previous provider. Tenant-to-tenant is the most fiddly case: two sets of identities, licences and domains have to be reconciled.
The hard parts: the domain can only live in one tenant at a time, and Teams and SharePoint content needs its own plan.
File shares, PSTs and public folders
The parts people forget until go-live. A mapped drive going back fifteen years, PST archives on individual laptops, and public folders holding contacts the sales team depends on.
Needs a decision: what moves, what is archived as-is, and what is genuinely finished with.
Already on Microsoft 365, badly
Not a migration so much as a correction: licences nobody reviewed, personal accounts holding company data, no multi-factor authentication and files scattered across private OneDrives.
Often better as: an IT audit first, so the work is based on what is actually there.
Choosing the approach
Which migration method suits your mail
For mail from Exchange there are three recognised routes. The choice follows mailbox count, how much downtime is tolerable and whether both systems need to work side by side. Our guide explains each in detail; this is the decision in short.
Everything moves at once
Suits smaller organisations where all mailboxes can move in a single planned window.
- Simplest to plan and to explain to staff
- One cutover, one set of instructions
- Practical up to a modest number of mailboxes
- Needs a genuinely quiet window
Batches over several weekends
Mailboxes move in groups, so a problem affects one batch rather than the whole organisation.
- Lower risk than moving everyone at once
- Lets you start with the willing and the low-risk
- Longer overall, with a period of split arrangements
- Needs clear comms about who has moved
Both systems working together
The on-premises server and Microsoft 365 coexist, sharing calendars and address lists while mailboxes move gradually.
- Least disruptive for users
- Free/busy and address lists keep working across both
- The most to set up and the most to decommission afterwards
- Worth it for larger or more complex estates
How the project runs
Discovery, pilot, cutover, then the fortnight that decides how it felt
The order is deliberate. Nothing moves before it has been measured, and nobody moves in bulk before a pilot group has worked normally on the other side for a few days.
Almost every bad migration was scoped from an assumption.The mailbox nobody mentioned, the archive nobody measured, the application that sends invoices through the old mail server. Discovery is cheap; discovering it at the cutover is not.
Discovery and scope
Count and size the mailboxes, list shared mailboxes, distribution lists, calendars, archives and public folders, and find every application or device that sends email through the current system.
Design and decisions
Agree the identity model, the migration method, where files will live, what is archived rather than moved, and which licences each person actually needs.
Build and secure the tenant
Set up the tenant, verify domains, create accounts and groups, and put multi-factor authentication and a sensible security baseline in place before any data arrives, not after.
Pilot with real users
Move a small, mixed group and let them work normally for several days. Mobile devices, signatures, shared calendars and printing to email all get exercised before anyone else is affected.
Main migration and cutover
Move the remaining data, then change DNS in the agreed window. Staff get instructions written for them rather than forwarded from a vendor.
Stabilise, then hand over
Stay close for the fortnight afterwards to clear the practical issues, then either hand back to your team with documentation or carry on supporting it.
Scope, cost and what we need from you
What drives the price, and what only you can decide
Migration quotes vary wildly because the scope does. These are the things that actually move the number, and the decisions that cannot be outsourced.
What drives the cost
Mailbox count and total data volume, what you are moving from, whether archives and file shares are included, how many shared mailboxes and calendars exist, and whether a hybrid arrangement is needed.
Quoted after discovery: we will give a range on a call, but a firm figure follows the inventory, because that is the only honest basis for one.
Microsoft licences are separate
Licences are bought from Microsoft or through a partner and are priced per user per month by plan. They are a running cost of the platform, not part of the migration work, and should be budgeted separately.
Worth reviewing: which plan each person needs. Over-licensing is common and is easier to fix before the move than after.
Decisions only you can make
What data is retained and for how long, who should have access to what, which old mailboxes belong to people who have left, and whether a department's filing habits carry over or get tidied on the way.
We will ask early: leaving these open until the cutover is what turns a planned move into a long one.
After go-live
Post-migration support can be a defined handover with documentation, or ongoing management under a support agreement. Our packages run from £29.95 to £94.95 per user per month plus VAT.
See: IT support packages, or Microsoft 365 support for what ongoing management covers.
Decide how much you want to take on
Running it yourself, or having it run for you
Plenty of organisations migrate themselves, and our guide exists for exactly that. The question is who absorbs the planning, the out-of-hours cutover and the fortnight of questions afterwards.
Swipe horizontally to compare both approaches.
| Question | Run it in-house | Supported migration |
|---|---|---|
| Discovery and inventory | Your team builds it, which is also the best way to learn the estate | Done as the first stage and written up |
| Choosing the method | Research against your mailbox count and tolerance for downtime | Recommended from the inventory, with the reasoning given |
| The cutover window | Usually a weekend of someone's own time | Scheduled and staffed as part of the work |
| If something stalls | You are debugging it live, out of hours | It is our problem to resolve, and we have seen the failure before |
| The fortnight afterwards | Falls on whoever is nearest, usually while doing their normal job | Part of the project, not an afterthought |
| Best when | You have in-house IT, time, and a simple estate | Mail is business-critical and nobody has spare weekends |
Learn from other people's cutovers
What actually goes wrong, and how it is avoided
Migrations rarely fail on the mail itself. They fail on the things around it that nobody put on the list.
The device that sends email
A multifunction printer scanning to email, a line-of-business application sending invoices, a website contact form relaying through the old mail server. All stop quietly at the cutover and nobody notices for days.
Avoided by: finding every sender during discovery and reconfiguring it as part of the plan.
Deliverability after the move
Mail starts landing in junk because the sending records were not updated to match the new platform. It looks like a mail problem; it is a DNS one.
Avoided by: updating SPF, DKIM and DMARC as part of the cutover. See how those records work.
Permissions that did not carry
A shared mailbox the whole team used, a calendar one person managed for three others, a folder with carefully set access. These do not always survive a copy and have to be rebuilt deliberately.
Avoided by: listing delegated access during discovery, then checking it in the pilot.
Security left until later
A fresh tenant with no multi-factor authentication, global admin rights handed out freely and no conditional access is a visible target, and migration is exactly when attackers watch for mailbox changes.
Avoided by: putting the baseline in before data arrives. See cyber security services.
Our clients
Trusted by growing teams
Businesses use UK IT Services for practical technology support, planned projects and ongoing assistance.
Discuss Your IT Requirements
Client feedback
What Our Clients Say
Real feedback from customers who have used our website, support and technology services.
Trusted customer feedback
★★★★★
4.7 out of 5 on Google. Verified reviews from businesses we support across Crawley, London and the South East. Read them in full on our Google Business Profile.
KF
Kymani FletcherGoogle review
Very happy with the website maintenance service. Updates are handled promptly and without disruption.
ZW
Zachary WattsGoogle review
Professional service with fast response times. Highly recommended.
GC
Giulia CostellaGoogle review
A highly capable professional who easily finds solutions to problems and learns quickly.
Latest insights
Guidance on Microsoft 365 and the move to it
Planning notes, licensing comparisons and the practical questions that come up once everyone is on the new platform.
Frequently asked questions
Microsoft 365 migration questions businesses ask first
Mostly about downtime, old mail and licences — the three things that decide whether a move feels controlled or chaotic.
What is a Microsoft 365 migration?
It is the move of your email, calendars, contacts and files from their current home — an on-premises Exchange server, a POP or IMAP mail host, Google Workspace or another Microsoft 365 tenant — into a Microsoft 365 tenant of your own, together with the identity, licensing and security setup that has to be in place around it.
How long does a Microsoft 365 migration take?
It depends on the number and size of the mailboxes, what you are moving from and whether files and archives are included, so we do not quote a timescale before the discovery stage. What we can say about the shape: data copying largely runs in the background, the cutover itself is a scheduled window rather than a long outage, and the fortnight after go-live is where the support effort concentrates.
Will we lose email during the migration?
Mail keeps flowing while the migration runs. The moment that matters is the DNS cutover, which is scheduled for a quiet window agreed with you; mail sent around that point is delivered once the change propagates. The risk worth planning for is not lost mail but mail that quietly stops being sent by a printer or an application still pointed at the old system.
Can you migrate from Google Workspace to Microsoft 365?
Yes. Mail, calendars, contacts and Drive content all move. The part that needs decisions rather than tools is collaboration: what becomes SharePoint and what becomes OneDrive, how Shared Drives map across, and whether Google Docs files are converted or kept in their original format.
Can you move us from one Microsoft 365 tenant to another?
Yes, and it is the most involved of the migration types. Tenant-to-tenant moves come up after acquisitions, demergers or a tenant set up badly by a previous provider. The complications are that a domain can only be verified in one tenant at a time, identities and licences have to be reconciled, and Teams and SharePoint content needs its own plan alongside the mailboxes.
What happens to our old emails and archives?
That is one of the decisions we ask about early. Mailbox content moves as a matter of course. PST archives sitting on individual laptops, public folders and very old mail are a separate choice: migrate them, archive them as they are, or confirm they are genuinely finished with. Leaving it undecided is what makes a cutover run long.
Do we need new Microsoft licences?
Yes — each person needs a licence on the plan that suits their role, bought from Microsoft or through a partner and paid per user per month. That is a running cost of the platform rather than part of the migration work. It is worth reviewing who needs which plan before the move, because over-licensing is common and cheaper to correct beforehand.
What support do we get after the migration?
The fortnight after go-live is treated as part of the project, because that is when the real questions arrive: signatures, mobile devices, a shared mailbox that has not appeared, a permission that did not carry over. After that you can take a documented handover to your own team, or keep the platform under ongoing support.
Can we do the migration ourselves?
Plenty of organisations do, particularly with in-house IT and a straightforward estate, and our phase-by-phase migration guide is written for exactly that. The honest question is who absorbs the discovery, the out-of-hours cutover and the support load afterwards, and whether that is a reasonable thing to ask of someone who already has a full-time job.
Plan your migration
Start with what you are moving from.
Tell us the current mail platform and roughly how many mailboxes. We will come back with the method we would recommend, what discovery would cover and a sensible cost range.
A recommended method, with the reasoningCutover, staged or hybrid, chosen against your mailbox count and how much disruption the business can absorb.
A pilot before anyone else movesReal users working normally on the new platform for several days, so the surprises happen to four people rather than forty.
The fortnight after includedSignatures, phones, shared mailboxes and permissions sorted while they are still fresh, not logged as new tickets.
Microsoft 365 migration enquiry
Fields marked * are required. If it is easier to talk it through, call 020 3048 4048.