Sonesta hired Mimecast, an e-mail service that acts as a central hub for Sonesta's e-mail. Local Exchange hosts serve users inside the building, which sends messages through Mimecast, rather than directly to the addressee. Mimecast data centers handle backup, security, spam-filtering, PCI and HIPAA compliance automation.

4. Private or public?

For Sonesta, the practical choice was private. Sonesta is restricted by HIPAA regulations and PCI security requirements, neither of which it felt it could satisfy running e-mail on a cloud service that allows virtual machines from several customers to run on the same physical server.

Except that someone else owns the data center, it's as close as possible to being Sonesta's own setup.

"We wanted a service that could make sure, if something went down, they could still get e-mail if they could get to the Internet, but we wouldn't have to maintain it in-house," Beggs says.