Microsoft issues a warning to users of Outlook for Microsoft 365, cautioning about potential connectivity problems between clients and email servers through Exchange ActiveSync after a recent January update. The issue arises specifically after updating to Version 2401 Build 17231.20182, causing Outlook to cease connecting when using the Exchange ActiveSync (EAS) protocol. The Outlook Team is actively investigating the matter, assuring users of a fix once the solution is identified.
Acknowledging the impact on users who rely on Activesync to connect to their cloud-hosted email servers, Microsoft has provided a temporary workaround. This solution involves either reverting Office M365 Click-to-Run installations to a stable version, with Version 2312 Build 17126.20132 being suggested, or switching to an Office Channel unaffected by the synchronization problem. The step-by-step process for this workaround includes temporarily disabling updates, running specific command lines in the command prompt dialog window, and checking if Outlook operates normally after the version revert process is completed.
In addition to the syncing issue, Microsoft is also actively looking into another problem that triggers security alerts in Outlook when attempting to open .ICS calendar files after applying the December 2023 Patch Tuesday Office security updates. This comes after Microsoft resolved a known Outlook issue causing connection problems for desktop and mobile email clients using Outlook.com accounts in the same month.
