Hence we mailed affected users to more urgently switch back to the native App, and already a few of them doing so gave immediate relief - enough for us to no longer worry about the system stability. Those using the native iPhone App (again) caused signifcantly (i.e., by an order of magnitude) less load and log volume. However, after several users had switched back, the situation remained the same. This was not that surprising during our first analysis when 'everybody' used that App.

But there was a correlation: All users with enormous hit counts came in with Outlook-iOS-Android/1.0 as user agent.

The culprit were tons of ActiveSync hits, sometimes several thousand per user per day. It did not get better by itself within a few days and the danger became imminent that our disks cannot hold the log volume of two days so that we'd be doomed if ever a daily backup should fail.Ĭonsequently, we took measures for a more detailed analysis. In parallel, we had been observing a significant and growing load on our Exchange and fast growth of transaction logs between daily backups (which clean the logs).

Once iOS 13.5 came out, we also suggested to switch back to the native App and uninstall the MS App. As a replacement we suggested the Microsoft Outlook App.

Many of my users use smartphones, mostly iPhones to access their in-house MS-Exchange mail accounts via ActiveSync.Īfter the recent security problems with iOS older than 13.5, we had recommended everybody to disable the native iPhone mail app.

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