Exchange 2010 EWS Proxy Event ID 16: No Applicable Client Access Servers
Applies to: Exchange Server 2010 Historical: This article covers the Exchange Server 2010 Client Access Server (CAS) proxy architecture. Exchange 2013 and later use a different Client Access / proxy model, so this specific troubleshooting flow should not be applied to current Exchange Server releases. In a multi-site Exchange 2010 environment, an Internet-facing Client Access Server could proxy Exchange Web Services (EWS) requests to a Client Access Server in the Active Directory site that hosted the mailbox. If Exchange could not identify a suitable Client Access Server in the destination site, the Application log could contain MSExchange Web Services Event ID 16 with a message similar to: Client Access server failed to proxy Exchange Web Services to Active Directory site because there are no applicable Client Access servers in the…

