I remembered that one of our admins was testing out an EWS Retention policy script and had installed the Exchange Web Services Managed API 2.2 on this box. The data field contains the error number. The System Event log was full of the following error:Ī process serving application pool ' MSExchangeServicesAppPool' suffered a fatal communication error with the Windows Process Activation Service. That led me to start checking what was up with EWS.
The CPU was at 100% usage, performance was terrible, and it even caused my Kemp load balancer to flap the virtual services on this server every 30 seconds or so. In particular the MAPI and EWS services. We recently migrated several hundred users from Notes to my Exchange 2016 CU2 environment and shortly after the migrations, one of my three mailbox servers was getting constantly hammered. This post is mostly for my own reference, but just in case you come across the same issue, I'll outline the problem and the fix.
