New Outlook Rollout: Two Scenarios

Microsoft 365 Apps for enterprise customers have at least two years, probably longer, before they must replace classic Outlook with new Outlook. The accompanying timeline shows two scenarios for rollout of new Outlook and shutdown of classic desktop Outlook for Microsoft 365 Apps for enterprise customers. Real events and dates will probably fall somewhere between these two scenarios.

ASAP. In this scenario (top), classic Outlook is gone from Microsoft 365 by Oct. 2026. The scenario assumes Microsoft drops classic Outlook as fast as possible given its announced plans. Most likely, customers will have more time to prepare for new Outlook than this scenario implies. However, Microsoft announced that new Outlook will be generally available (GA) Aug. 1, 2024, which is consistent with the ASAP scenario.

Slow. In this scenario (bottom), classic Outlook is gone from Microsoft 365 by July 2027. This scenario assumes that Microsoft takes an extra three months before each major event to collect data, fix migration blockers, and consult customers. The scenario is probably too conservative, and new Outlook will reach GA ahead of schedule, compared to the scenario.