Zero-Downtime Microsoft 365 Migration for Central London Law Firm
Zero downtime during migration — all 65 users maintained email access throughout. We delivered this outcome for Central London Legal Practice (65 users) by combining Microsoft 365, Exchange Online, SharePoint into a single strategic engagement.
What Central London Legal Practice was facing
A central London law firm was running an aging on-premises Exchange 2013 server that had reached end of support, leaving them vulnerable to security threats and non-compliant with SRA and Lexcel requirements. Their email was unreliable, with frequent outages during critical court filing deadlines, and their lawyers couldn't access email securely from court or home. They needed a zero-downtime migration to Microsoft 365 that would preserve all case correspondence, maintain legal privilege, and ensure SRA compliance — without disrupting billable work or court deadlines.
How we solved it
We designed a phased Microsoft 365 migration strategy using a hybrid configuration that maintained email continuity throughout the transition. We began with a full audit of their Exchange environment — 65 mailboxes totalling 180GB, shared mailboxes for practice addresses, and public folders containing years of case correspondence. We configured Microsoft 365 Business Premium with advanced security features, implemented Mimecast email security for phishing and impersonation protection (critical for preventing conveyancing fraud), and designed a SharePoint document management system to replace their aging file server. The migration was executed in three waves over two weeks — partners first, then associates, then support staff — with each wave completed over a weekend. We provided tailored training for each group, focusing on Outlook, Teams, and SharePoint for legal collaboration.
What we delivered
Tools and skills applied
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Related services & insights
The legal services expertise and technical capabilities behind this engagement.
Services
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Enterprise-grade email security with Mimecast to stop phishing, ransomware, and business email compromise.
IT & Cloud Infrastructure Migrations
End-to-end IT and cloud infrastructure migration services — from assessment and planning to zero-downtime execution and post-migration optimisation.
Microsoft 365 Support
Microsoft 365 support services — expert setup, zero-downtime migration, security hardening, and ongoing management of your productivity suite.
Tech Insights
Microsoft 365 Migration: A Step-by-Step Guide for SMEs
Migrating to Microsoft 365 without downtime or data loss. The exact phased approach our engineers follow, from audit to go-live.
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Sources & further reading
Independent guidance from UK regulators, standards bodies and technology vendors that underpins the advice on this page.
- Microsoft LearnMicrosoft 365 documentationAdministration, security and compliance reference for Microsoft 365 tenants.(opens in a new tab)
- Microsoft LearnZero Trust security guidanceThe verify-explicitly, least-privilege model we apply to identity and access.(opens in a new tab)
- National Cyber Security CentreCloud security guidancePrinciples for selecting, configuring and operating cloud services securely.(opens in a new tab)
- Microsoft LearnAzure documentationReference documentation for the Microsoft cloud platform.(opens in a new tab)
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