Microsoft fixed an issue that caused some Microsoft 365 users’ Outlook desktop clients to no longer connect to their email servers via Exchange ActiveSync.
Exchange ActiveSync (EAS) is a synchronization protocol used by Microsoft Exchange to give users access to email, calendars, contacts, and tasks.
EAS uses HTTP and XML to communicate and synchronize data between Exchange servers and mobile devices. By default, EAS is enabled on new users’ mailboxes, and disabling it may prevent users from syncing their mailboxes with their mobile devices.
One user report states, “You must use Activesync to connect to cloud-hosted email servers. Other syncs may not be affected.”
This known issue only affects Outlook for Microsoft 365 users who updated their client to version 2401 build 17231.20182.
Microsoft says the known issue has been resolved in version 2402 build 17328.20068 or later, and asks customers to install the update by clicking Update Now under File > Office Account > Update Options. I am asking you to do so.
Before resolving the issue, Redmond also provided affected users with a temporary fix to restore their Outlook desktop client. This required reverting the Office M365 Click-to-Run installation to an unaffected Office build (recommended build is version 2312 build 17126.20132) or switching to the following build: Office channels that did not experience this sync issue.
“If you worked around the issue by reverting to a previous build,[ファイル]>[Office アカウント]>[更新オプション]>[更新を有効にする]then re-enable the update,” the company announced today.
Microsoft is also currently investigating an issue where Outlook triggers a security alert when you try to open an .ICS calendar file after installing the December 2023 Patch Tuesday Office security update.
Last month, Microsoft fixed another known Outlook issue that caused connectivity issues for desktop and mobile email clients using Outlook.com accounts.
In December, Microsoft addressed two additional bugs. One caused email sending problems for users with many folders, and the other caused him to crash Outlook while sending emails from his Outlook.com account.
