Micorosoft crm outlook configuration to user in Dynamic crm on-permises-2015

Hi, 

I have downloaded the Microsoft CRM tool for Outlook and installed to it. but while connecting it  gives an error saying 

There is a problem communicating with the Microsoft Dynamics CRM Server. The server might be unavailable. Try again later. If the problem persists, contact your administrator.

I tried all solution for internet but did not work..

So my question is does this error occur if we have many organisation in a single server system or all have a same port number 80  .

Does this effect the outlook any way . And also please let me know how to configure mail-server in the dynamic crm . 

Thanks 

Leonard Francis