Email Migration – Case Study


Thistle Insurance Limited (Thistle) is a UK Insurance Broker, with a head office in Gloucester and satellite offices throughout the UK. It currently employs around 250 employees.


When Thistle Insurance was acquired from its parent company a transition period was agreed for Thistle to be migrated from the parent companies’ IT environment. Current and historic email was hosted by the parent company on their in-house Exchange 2010 system and in-house Symantec mail archiving system. The challenge was to migrate 250 employee mailboxes to Office 365, untangle 50 domain names, keep 100% email receipt and working hours availability during the migration.

What we did

With the parent company mandating that no migration tools could be deployed within their environment we made the decision to isolate the existing archiving and import it to the destination Mimecast archiving system. Alongside this we created an approach to migrate the current e-mail accounts and 2 years of historical e-mails to Office 365 in tranches. Alscient guided this process to ensure the best outcome for the business including:

  • The migration of 12 years’ worth of archived email into Mimecast.
  • Extracting and importing of 2 years’ worth of e-mail / outlook items into Office 365.
  • The migration of 50 e-mail domain names into Office 365.


Despite the significant constraints, including being limited to PST exports, the migration to the end users went very well with David Rarity (Thistle Migration Programme Manager) commenting:

“On behalf of the receiving business, I would like to extend thanks to all involved for producing a quality implementation which has generated minimal business disruption – we have genuinely been bowled over by the expertise and attitudes displayed by the team. Not everything went seamlessly, but the efforts of the team to resolve / explain have been excellent – thank you !”