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ActiveSync throttling / blocking issues - Office 365 and Android 4.4.2 on a Samsung Galaxy Note 3
I have been having issues with a particular user and his Samsung Galaxy Note 3 phone. We are using 'Office 365 / Exchange Online' but a lot of this topic applies to on-premise Exchange Server as well.
I enabled ActiveSync logging for the user's device via OWA > Settings > Phone This is a pretty good link about how to collect EAS logs: Exchange ActiveSync Mailbox Logging - Jason Slaughter - Site Home - TechNet Blogs
Note: though you can also retrieve the logs via OWA, I found this powershell command to be beneficial:
Get-MobileDeviceStatistics -Mailbox alias -GetMailboxLog:$true | Out-File c:\scripts\test.txt
This is because:
-Sometimes collecting long duration logs from OWA results in the emailed attachment coming through as an empty .gzip file. The text output doesn't seem to suffer from this
-Running the command produces the text file as well as sends you an email (instead of emailing the user)
-Using the command doesn't disable the logging; using OWA to retrieve logs stops the logging
Using this parser for the log.txt files is really handy: https://mailboxlogparser.codeplex.com/
The log shows a cyclical behavior- about 5 to 10 minutes of success followed by about 20-25 minutes of failure. When the device is blocked, the logged events go from HTTP 200 success status codes to:
Http Status: 503
The individual blocked transactions also contain:
It appears Office365/Exchange Online is throttling this active sync device.
I also noticed that a good number of the ‘200 – success’ requests have the identical ‘synckey’. The identical requests appear to happen 60 times over roughly 4 seconds- followed by the ‘503 – blocked’ state.
One step we took was to get the user a second smartphone on a separate line. This time we selected an iPhone 5s and set up the activesync pairing. So far the iPhone has not had any active-sync issues.
I turned on Active-Sync logging multiple times. The user’s Apple iPhone continues to operate properly. The Samsung (android) continues to exhibit the same problem. The cycle of connectivity stays pretty consistent in the logs. 5 to 10 minutes of ‘allowed’ connectivity followed by 20-25 minutes of ‘blocked’ status.
Removing and re-adding the user's Microsoft Active-Sync account multiple times does not help. Sometimes the 'remove/re-add process' would cause the phone to operate properly for a couple days- then it would revert to the connectivity issue. This was also the case when using different Samsung Galaxy Note 3 phones.
It appears that Android 4.4.1 and 4.4.2 (KitKat) introduced activesync problems. I’ve included some links below that discuss the issue. People cite problems ranging from inability to initially pair, to activesync connectivity being interrupted, to my specific issue- repeated identical ‘Sync’ requests that lead to throttling.
A mobile device intermittently can't connect to Exchange Online
Android 4.4/KitKat Exchange ActiveSync problems; fixed in 4.4.1? | Paul's Down-Home Page
Kitkat causes ActiveSync headaches for Android users | Tony Redmond's Exchange Unwashed Blog
Android KitKat 4.4.2 Exchange ActiveSync (EAS) Error Solved | Whatever IT Takes. Real People, Real Service.
Some posts online have referred to these steps to correct the problem:
Here are the easy steps to fix the EAS sync error in Android KitKat:
• Go to system Settings >> Accounts >> Select “Corporate”
• Press your menu button or the three dots on the upper right screen >> Select “Sync Now”
• Open up your notification window by swiping down from top of your screen.
• There should be some kind of security alert in the notifications >> Select option with activate now.
In my testing, the steps do not work on the Samsung Galaxy Note 3. I was however able to get the ‘Security Alert Notification’ by removing the activesync account and recreating it. Unfortunately I was only able to get to the 'security notification' on a different user's Samsung note 3. When I removed and added the Active-Sync account for the affected user, no such prompt came up in the 'notifications' window. This last time, the user hit the same 'blocking' problem, but as soon as the new activesync pairing was done. That's actually better though than thinking the problem is fixed- then having it come back days later.
One oddity that I have encountered: The affected phone is running Android 4.4.2. The phone is at the latest
update available for it. The odd item is that I have several other users on Android 4.4.2 and they are not having the same issue. One of those phones is an identical Samsung Galaxy Note 3 and identical version of Android/rom etc.
Prior to finding the likely cause being an android firmware issue, I spent about 2 hours with Microsoft Support. They were unable to suggest any causes or solutions for the problem at hand. They did confirm the device is being throttled according to the logs. I also thought the user's per folder item counts in his large mailbox could be an issue. I have ruled those out however.
If you have a similar issue or have found a resolution for this- I'd love to hear about it. Thank you.