In order to configure your McAfee Firewall to work with IncrediMail, launch the security software, click Firewall below Updates and select Settings. Click Internet Connections for Programs below Firewall History and then Browse. Navigate to (C:) > Program Files > IncrediMail > bin folder and add the IMApp.exe, IncMail.exe, ImNotify.exe and ImpCnt.exe files.
In other versions of the antivirus, you need to go to Personal Firewall+ and select View the Internet Applications List. After that, press New Allowed Application, navigate to bin folder and add the same files.