Private Equity – Hosted Exchange migration to Office365 & Mimecast

Our existing client, a boutique Private Equity company, specialising in emerging retail brands, had begun life with a Hosted Exchange email solution.

Due to the FCA SYSC Rulebook requirements on archiving and supervision, the low cost email set up that had worked for the client when they were not regulated, did not when they eventually became regulated.

We proposed an Office 365 based solution to manage the email.  For FCA compliance purposes we implemented a Mimecast Archive & Security service.

As well as the enhanced email infrastructure we took the opportunity to unify the clients’ Windows Domain and Office 365 accounts with a Single Sign-On.

Additionally we secured the Office365 logon with Multi-Factor Authentication (‘MFA’) to comply with FCA Guidelines and Recommendations

Though not a very large or complex company, there were a number of considerations:

  • Approximately 200GB data to migrate & ingest to the Archive.
  • Archived mailboxes on an ageing local Windows Small Business server.
  • Staff with multiple levels of access to other mail files.
  • Staff in geographically diverse locations – UK, Europe, US and Asia.
  • 24/7 working hours due to time zone differences with a limited the migration window.
  • Managing MX record change and propagation to minimise any downtime inconvenience.
  • Heterogeneous Mac, PC and iOS devices.
  • Non technical user base.

Our Solution

Given the challenges our aim was minimum user interaction and maximum automation to provide a seamless service to the client.  Consequently we used a number of tools and methods:

  • Cloud based migration tools to automate the data transfer and facilitate co-existence between the Hosted Exchange and Office 365. This allowed us to mirror the mailboxes between the Exchange server and Office 365 until the migration was complete.
  • Tools to convert archive ost to pst files and then upload all the archived mail to the Mimecast cloud data archive.
  • Microsoft Office Deployment Tool and Group Policy configuration to deploy Office 2016 to Windows PCs.
  • Group Policies to configure localised and company specific Microsoft Office options.
  • Azure AD Connect to synchronise client Windows Domain with Azure & Office 365
  • TeamViewer remote support toolset to configure and test client machines.
  • End User training with bespoke User Guides, On-Site Personalised Training and demonstrations as well web video and training links.


  • Initial migration and testing done a week in advance of the actual user migration
  • All user and shared mailboxes successfully migrated to Office 365 in a 4 hour period.
  • DNS MX records updated with no loss of email
  • Mimecast service fully implemented
  • All client computers updated to latest version of Office 365 Pro Plus
  • Unified Single Sign-On for Windows Domain and Office 365
  • MultiFactor Authentication for Webmail and email
  • Robust Data backup and redundancy provided by Microsoft


  • Reliable and secure access to email from any location and using any devices.
  • Enhanced mail hygiene and security as well as archiving and mail supervision using Mimecast.
  • Access to the full Office 365 suite of applications for Windows, Mac OS X, iOS and Android devices both as local applications and through the Microsoft Office 365 web portal.
  • Lower ongoing support costs
  • Users able to use Skype, OneNote and OneDrive to increase productivity and collaboration.
  • Free and timely security patches via Microsoft licensing.
  • Zero infrastructure and maintenance costs.
  • Reduced costs by maximising the use of E1 & E3 licenses as appropriate or necessary and converting old User Mailboxes to Shared Mailboxes (no license required)