Microsoft has released a public preview of Exchange 2019, the on-premises email server software the company will start selling later this year.First promised in September 2017, when Microsoft announced that sneak peeks of perpetual versions of the Office applications - Word, Excel, Outlook and the like - and Office-centric servers would land in the middle of the following year, Exchange 2019 is set to launch sometime this fall.[ Further reading: First look: Office 2019 likeliest new features ]Microsoft has already issued previews for Office 2019 for Windows and the Mac, although both betas have been aimed at commercial customers, not consumers.