Emails being randomly blocked by Norton 360 in OUTLOOK 2007

I am using Outlook 2007 on two computers one running Windows XP and other Windows 8.1 and on both machines odd emails do not arrive in the inbox or Junk box locations. On many occasions these emails are important and not spam. This behaviour is becoming extremely irritating and will lead me not to renew the software when the licence expires.

However they do arrive on my mobile phone running an android system and on a desktop running windows 7 with a competitor virus product.

So the only difference between receiving these emails and not receiving them is NORTON 360. 

So how can I tweak the settings of Norton 360 to allow these emails through. (Settings in Outlook use POP3 email )

Many thanks