Hello,

I have a single server environment with Exchange 2013 CU7. I've recently been experiencing both intermittent activesync issues and server crashes whenever receiving 24 MB files from external emailers. Originally, I posted a question here: https://social.technet.microsoft.com/Forums/office/en-US/2e8b2abe-411b-453e-b0f0-cf6b776fdd32/exchange-server-2013-cu7-back-pressure-version-buckets?forum=exchangesvradmin

concerning Back Pressure version buckets. I have since tried to disable shadow redundancy and am still having these issues. I have found some other issues that I think relate to the version buckets problem. I thought I'd start a new post in light of my discovery of these Health issues.

A few days after disabling shadow redundancy, we had another server crash/delay caused by a large email received from an external address. Right around the time of the crash I am seeing event ID 5011. Articles on this event advise to troubleshoot exchange server health and to use IIS debug to troubleshoot app crashes. I ran the shell command "get-serverhealth servername" and found out that the alert values for "ActiveSync," "ActiveSync.protocol," and "FrontendTransport" are all "unhealthy."

Some more digging to find out what monitors caused the alerts found the following:

OnPremissesInboundProxyMonitor

OnPremisesSmtpClientSubmissionMonitor

ActiveSyncCTPMonitor

ActiveSyncDeepTestMonitor.

Troubleshooting steps here recommend Recycling app pools, IIS and server power. https://technet.microsoft.com/en-us/library/ms.exch.scom.activesync(v=exchg.150).aspx#EXP

None of these has returned the sets to "Healthy."

Their last step is to contact Microsoft. My plan is to run updates this weekend and contact Microsoft to troubleshoot after as I'm sure this will be their first recommendation when I open the case.

I'm also going to install IIS debug diagnostic tool to see if I can get more information from crash dumps if they continue.

Anyone have any other recommendations?

Thanks.