If the above does not fix the problem, try the following ...
It is important to set the outlook setting while NEO is not active.
Close NEO and Outlook, along with any other email-aware programs.
Wait for one minute and then open Outlook alone.
When the dialog comes up on a Send/Receive, check the checkbox saying "Don't show this dialog box during Send/Receive".
If the above does not fix your problem, then …
Always have Outlook running when you start NEO, and keep Outlook running while you are using NEO. You can ensure this by going to NEO Tools menu | Options and checking the option to start NEO when Outlook starts.