Short · checked 29 September 2026
The invite-only email app that became Outlook on your phone.
An iPhone email app listed in February 2014 that Microsoft bought ten months later and used as the code base for Outlook on iOS and Android.
Acompli arrived on Stompstart on 21 February 2014 with a pitch aimed squarely at the overloaded professional: "Acompli empowers professionals to do more and defer less from mobile email." The listing described one iPhone app that pulled advanced email, full calendaring, file sharing, predictive search and smart contacts together, and invited readers to request an early invite. The image uploaded with it shows three iPhones side by side: an inbox, an open message and a calendar.
That combination was the whole argument of the listing: the phone could be where email work got done, not only where it was sorted for later.
Nine months after the listing, Microsoft announced on 1 December 2014 that it had acquired Acompli, describing it as a provider of mobile email apps for iOS and Android.
What happened next is the unusual part: Acompli did not disappear into Microsoft. It became the product. On 29 January 2015, Microsoft launched a new Outlook for iOS and a preview for Android and told Acompli's users that Outlook would feel familiar, "as we're developing the apps from this code base." In the same post it named former Acompli chief executive Javier Soltero general manager of Outlook.
The Acompli name is gone, and acompli.com no longer serves a site. The app it grew into is not: Microsoft Outlook for iPhone was still receiving updates in September 2026.
The Stompstart page that survives in the Wayback Machine was captured on 17 March 2015, after the acquisition. The listing itself, and its image, date from February 2014, when Acompli was still asking for invites.