Microsoft 365 Migration: Zero-Downtime Migration from AMVIA
AMVIA migrates UK businesses to Microsoft 365 with zero planned downtime — moving email, files, Teams, and legacy system data whilst staff continue working throughout. We manage the full migration lifecycle from assessment through cutover and post-migration support.
Why Migration Needs Expert Management
Moving to Microsoft 365 involves migrating email history, shared file storage, user accounts, and potentially legacy on-premises server data. Done without a structured plan, migrations cause data loss, extended downtime, and user disruption. AMVIA manages every step — from initial assessment and data mapping to cutover coordination and post-migration support — ensuring your business experiences a transition, not an outage. Microsoft 365 has nearly 345 million paid subscribers globally in 2025. An estimated 1.9 million UK businesses use Microsoft Teams.
Explore Microsoft 365 servicesWhat a Microsoft 365 Migration Involves
Migrating to Microsoft 365 typically involves moving email from an existing system (Exchange on-premises, Google Workspace, hosted email), migrating file storage from network shares or on-premises file servers to SharePoint and OneDrive, setting up Microsoft Teams, configuring security and compliance policies, and onboarding users to new workflows. The complexity depends heavily on your starting point and the volume of data being moved.
Compliance costs for newly in-scope entities are estimated at £350 million to £600 million in aggregate initial investment (UK government impact assessment). (Skadden)
Data centres with rated IT load of 1 MW+ (enterprise: 10 MW+) (Skadden)
94% of small businesses in the UK experience poor internet connection; 91% encounter internet outages (survey of 500 UK SME decision-makers, Zen Internet/YouGov 2024). (Smetoday)
AMVIA begins every migration engagement with an assessment of your current environment — what systems are in place, how much data needs to be migrated, what dependencies exist (shared mailboxes, distribution groups, calendar resources, room mailboxes), and what the acceptable migration window is. This assessment informs the migration plan and highlights risks that need to be addressed before cutover.
Email Migration
Email migration is typically the highest-priority element. Staff need continuous access to email during migration, and losing email history or experiencing delivery interruptions is unacceptable for most businesses. AMVIA uses staged migration approaches that synchronise email to Exchange Online before cutover, meaning staff can be moved to their new M365 mailboxes with minimal interruption and their full email history already in place.
Mailbox types that need specific handling include shared mailboxes, distribution lists, room and resource mailboxes, and contacts. AMVIA maps all of these in the pre-migration assessment and ensures each is correctly configured in Exchange Online before cutover.
File Migration
Moving files from network shares or on-premises file servers to SharePoint and OneDrive requires careful planning around permissions mapping, folder structure, and large file handling. AMVIA uses Microsoft's SharePoint Migration Tool and other validated tools to migrate file data at scale, preserving permissions and metadata where possible.
Before migration, AMVIA reviews the existing file structure and recommends whether SharePoint team sites, OneDrive, or a combination is the right destination for different data types. Governance and permissions are configured in SharePoint before files are migrated, so the structure is correct from the start.
Microsoft Teams Deployment
Teams is more than a messaging platform — it is the collaboration hub that connects email, files, meetings, and calls. AMVIA configures Teams alongside the M365 migration, establishing team structures, channels, and governance policies before staff transition. This includes external sharing policies, guest access configuration, and Teams lifecycle management to prevent uncontrolled team proliferation over time.
Security Configuration
A migration is an opportunity to configure Microsoft 365 to a strong security baseline from the outset. AMVIA deploys MFA, Conditional Access policies, Defender for Business, and DLP policies as part of the migration engagement — so the new environment is secure from day one rather than having security added as an afterthought. Many businesses that migrate without specialist help inherit a weakly configured M365 environment that requires later remediation.
User Training and Adoption
Technology migration is only successful if staff adopt the new tools effectively. AMVIA provides training material and, where required, live training sessions covering Outlook on the web, Teams, OneDrive, and SharePoint. The goal is to ensure staff are productive in the new environment from the first week, rather than struggling with unfamiliar tools and reverting to old habits.
Post-Migration Support
The immediate post-migration period is when most issues surface. AMVIA provides dedicated post-migration support for 30 days following cutover, resolving user issues, addressing any migration artefacts, and completing any deferred items from the migration plan. After this period, ongoing support transitions to AMVIA's standard managed IT service.
AMVIA M365 Migration: What's Included
End-to-end migration management from assessment to post-cutover support.
Pre-Migration Assessment
Current environment documented — mailboxes, files, dependencies, and migration risks identified before work begins.
Email Migration
Staged email migration to Exchange Online with full history, shared mailboxes, and distribution groups handled.
File Migration to SharePoint
Network share and file server data migrated to SharePoint and OneDrive with permissions preserved.
Teams Configuration
Teams structure, governance policies, and external sharing configured alongside the migration.
Security Baseline Configuration
MFA, Conditional Access, Defender for Business, and DLP configured from day one of the new environment.
30-Day Post-Migration Support
Dedicated support for a month following cutover to resolve user issues and complete migration tasks.
M365 Migration Readiness Checklist
Key steps to address before starting a Microsoft 365 migration.
All user mailboxes inventoried
Including shared mailboxes, room mailboxes, and distribution groups that need to be migrated.
File data volume assessed
Total data to be migrated quantified — affects timeline, tool selection, and project planning.
Microsoft 365 licences selected and purchased
Correct licence tier confirmed for all users — Business Premium recommended for security controls.
DNS change process confirmed
MX record cutover plan agreed — this is the point at which email flow switches to Microsoft 365.
Legacy system dependencies documented
Applications or services that send or receive email via the current system identified for reconfiguration.
User training scheduled
Staff training planned to coincide with cutover — reduces post-migration helpdesk volume.
M365 Migration FAQs
Duration depends on the volume of data and the complexity of the current environment. For a business of 20 to 50 users migrating from a hosted Exchange service with standard file storage, a well-planned migration typically takes three to six weeks from assessment to cutover. Larger environments, legacy on-premises servers, or complex application dependencies extend this timeline. AMVIA provides a project plan with timelines during the assessment phase.
AMVIA's migration approach is designed for zero planned email downtime. Email is synchronised to Exchange Online before the DNS cutover, meaning all historical email is already in place when staff switch to the new system. The DNS cutover itself — when email delivery switches from the old system to Microsoft 365 — typically takes 15 to 30 minutes for propagation. Staff continue working in the old Outlook profile until they are switched to M365. <strong>94% of small businesses</strong> in the UK experience poor internet connection; 91% encounter internet outages (survey of 500 UK SME decision-makers, Zen Internet/YouGov 2024). <em>(Smetoday)</em>
During the migration period, email continues to deliver to your existing mail system and is synchronised to Exchange Online automatically. At the cutover point, inbound email routes to Microsoft 365. Any email sent during the DNS propagation window is handled by the old system and synchronised across. AMVIA monitors email flow during and after cutover to confirm delivery is working correctly.
Yes. Cross-platform migrations from Google Workspace (Gmail, Google Drive, Google Calendar) to Microsoft 365 are a standard AMVIA service. These migrations require specific tooling to convert data formats correctly and handle calendar and contact migration that does not apply to Exchange-to-Exchange migrations. AMVIA will assess the specific complexity of a Google-to-Microsoft migration during the pre-migration assessment.
Plan Your Microsoft 365 Migration with AMVIA
AMVIA will assess your current environment, design a migration plan, and deliver a zero-downtime move to Microsoft 365. Contact our team to start the conversation.
Related Microsoft 365 Resources
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Managed Cybersecurity Services
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Managed Desktop Services
AMVIA manages devices alongside your Microsoft 365 environment for a complete managed service.