All Troubleshooting steps / How To:
o Notes: Good idea to clear out the Lync/Skype File Cache, search for KB on Skype File Cache
o Notes: Skype For Business Configuration Information will show if they are missing the EWS & MAPI for any users.
This issue has to do with their Outlook Exchange Integration.
Example of what to look for:
o To Check Go To: Skype Icon in the task bar > hold left control & shift button and click on the Skype Icon > Click on the Skype For Business Configuration Information.
o Check to see if MAPI and EWS status. If ther is no ok it is missing that is the issue,
it shows OK issue could be something else look to escalate