What to do when a third-party application is interfering with Exchange Server connection ?
There are possible chances that your antivirus application might be interfering when you are trying to connect MS Outlook to Exchange Server. To resolve such a problem, Launch MS Outlook in Safe Mode of your Windows machine. Remove all the installed add-ins in Outlook. For doing this, go to File >> Options >> Add-ins >> COM Add-ins >> Manage >> Go >> Checkbox Clear >> OK. Also, check your anti-virus settings.