EWS Connect Error 401 Unauthorized – InfoBridge
kb.infobridge.com › hc › en-usOct 12, 2017 · Written by Support InfoBridge Overview When connecting to EWS (Exchange Web Service) you could receive a 401 error, saying you are not authorized. How to Check permissions for "Authenticated Users" on your CAS's directories for your OABs (default C:\Program Files\Microsoft\Exchange Server\ClientAccess\OAB\<guid of OAB>).