Moving business email is not like installing a new app. If messages stop arriving, staff lose access to shared files, or Outlook keeps asking for passwords on Monday morning, the disruption is immediate. This Office 365 migration guide explains how London businesses can move email, contacts, calendars and files with less risk and less downtime.
Office 365, now commonly branded as Microsoft 365, can give a small or growing business better email security, shared working tools and easier access across office, home and mobile devices. The move is worthwhile, but only when the planning is as careful as the technical work.
Start with the right Office 365 migration plan
The best migration method depends on what you use now, how much data you hold and how your staff work. A five-person office using one old email provider has very different requirements from a company with several domains, shared mailboxes, archived email and staff working across Windows PCs, MacBooks and phones.
Before moving anything, make a clear inventory. Record every email address, shared mailbox, mailing list, contact list, calendar, domain name and device that connects to company email. Also check who has access to important folders and files. It is common to find a former employee’s account still forwarding messages, a shared inbox being accessed with one password, or business files stored only on one person’s desktop.
Your migration plan should answer three practical questions: what will move, when will it move, and what will staff need to do afterwards? If the answers are vague, the migration is not ready to begin.
Choose a migration approach that suits the business
Most smaller businesses use an IMAP migration when moving email from a hosted mailbox or older provider. This transfers email folders but may not bring across contacts, calendars, tasks or rules. Those items may need to be exported separately or rebuilt.
A cutover migration can suit a straightforward move from an older Microsoft Exchange setup where all mailboxes move at once. It is quicker to manage but requires good timing because everyone changes over together. For larger offices or businesses that cannot accept a single switch-over point, a staged or hybrid approach provides more control, although it takes more planning and technical knowledge.
There is no one-size-fits-all answer. The priority is protecting your business data while keeping staff able to send and receive email throughout the change.
Prepare accounts, licences and security first
Create user accounts and assign the correct licences before the data migration starts. Make sure every person has the services they actually need. Some staff may only need email and web versions of Office applications, while others require desktop apps, Teams meetings, shared storage or advanced security features.
Set up shared mailboxes properly rather than relying on one generic login for reception, accounts or sales. A shared mailbox gives the right people access while keeping a clear record of who sent or handled a message. It also means you can remove access quickly when someone leaves.
Security should be in place from day one. Turn on multi-factor authentication for all users, especially directors, finance staff and administrators. A password alone is no longer enough protection for a business mailbox. Use a strong administrator account that is separate from normal daily email use, and keep recovery details securely recorded.
It is also sensible to review conditional access, spam filtering and external forwarding rules. These settings can be adjusted as the business grows, but basic protection should not wait until after a phishing incident.
Clean up before you transfer data
A migration is a useful opportunity to remove clutter rather than copying years of unnecessary material into a new system. Ask staff to delete unwanted drafts, duplicate folders and old newsletters where appropriate. Check whether former staff mailboxes need to be retained for legal, commercial or customer-service reasons.
Do not delete records just to make the transfer faster. Customer correspondence, invoices and project information may have retention requirements. Where archives are needed, agree whether they should stay accessible in Microsoft 365, be exported for secure storage, or remain with the old provider for a defined period.
Back up important data before the migration. This includes email, contacts, calendars and files stored locally on PCs or Macs. Although cloud services are reliable, a separate backup and tested export provide reassurance if an account is configured incorrectly or a file is accidentally removed during the change.
Move email without disrupting the working day
The technical switch usually happens when your domain’s DNS records are changed. These records tell the internet where to deliver your email. It is a small change with a big effect, so it should be planned outside the busiest part of the working day wherever possible.
Before changing the records, lower the DNS time-to-live setting if your provider allows it. This can help the new settings take effect sooner. Then add and verify your domain in Microsoft 365, complete the required DNS records and test delivery carefully.
A sensible approach is to migrate data in advance, then perform a final synchronisation shortly before the email switch. This reduces the number of messages left behind on the old system. Keep the previous email service active for a short agreed period, rather than cancelling it as soon as the new mailboxes appear to work.
After the switch, test incoming and outgoing email using both internal and external addresses. Check that messages from customers do not land in junk folders, that website contact forms still arrive, and that staff can send from shared mailboxes where required. If your business sends newsletters, invoices or automated notifications, test those systems too.
Set up every device and application
A successful migration is more than moving mailboxes. Staff still need access on their laptops, desktop PCs, mobile phones and tablets. Outlook profiles may need to be recreated, old passwords cleared from saved credentials and mobile mail apps reconnected.
Mac users may be using Outlook for Mac, Apple Mail or both. Windows users may have several Outlook versions in the office. Each setup behaves slightly differently, so testing one device does not prove every device is ready. Include remote workers in the plan, particularly if they are working from home on personal broadband or unmanaged equipment.
Review printers, scanners, CCTV alerts, website forms and accounting packages that send email. Older devices often use an outdated SMTP setup and may stop sending after the move. This is one of the most frequent oversights in a business email migration.
Give staff a simple changeover plan
Technical work can be perfect and still create frustration if users do not know what is changing. Send staff a short, clear message before the migration. Explain the date, likely impact, what they need to do with passwords and where to get support. Avoid overwhelming people with technical detail.
On the day, provide an easy route for reporting issues. Common early problems include repeated sign-in prompts, missing shared mailbox permissions, email autocomplete showing old addresses and OneDrive files not syncing. Most are quick to resolve when there is someone available to help.
A brief follow-up session can also help staff use Teams, OneDrive and shared calendars correctly. Moving to Microsoft 365 is an opportunity to improve the way the team works, but forcing too many new habits on the same day as an email move can cause unnecessary confusion.
Check the migration after the first week
The first few days reveal issues that testing may miss. Review message trace information, failed sign-ins, spam reports, storage limits and users who have not enrolled in multi-factor authentication. Check that former staff accounts are disabled and that new starters have the right access.
You should also confirm that your backup, retention and recovery arrangements match the business’s needs. Microsoft 365 provides valuable built-in protection, but businesses should understand what can be recovered, for how long, and who is responsible for doing it.
For London businesses with limited in-house IT support, A2z Computer Solutions can help plan the move, configure devices and deal with the practical problems that hold up a working day. An engineer can support your office on site, so staff are not left waiting while email, WiFi or Outlook access is restored.
A well-run migration should feel uneventful to your customers. Plan carefully, test the details that matter and give your team a clear point of support, and your new Office 365 setup can start delivering value from the first working day.