Facility services giant ISS has revealed plans to bring 25,000 staff worldwide onto the hosted email component of Microsoft's Office 365.
The Danish company had over half a million employees, including 22,000 in Australia.
Most were not deskbound but involved in facility services like reception, cleaning, mail delivery, grounds and building maintenance.
ISS' global IT sourcing head Morten Wagner said that Exchange online would replace a mix of Exchange premise, Lotus Notes and lesser-known systems.
About 8,000 staff have been migrated to Exchange Online. The remaining 17,000 – sitting in offices in 44 countries – would follow in the second and third quarters of this year.
Microsoft launched its Office 365 cloud service this week, for which Australian users would pay a premium compared to those in other countries.