Restricting Text Messages to Contact List

I've downloade the paid version of Norton Mobile Security, and one of the reasons was for the call and text blocking feature.  I have had to have Verizon block texting altogether on my phone because I was getting almost constant texts from payday lenders and other spammers (at 20 cents a pop).  I would block one number, only to have them send with a different number.  Last week, I got a call from a number I didn't recognize, but didn't pick it up because I was busy at the time.  Later, I tried to call it back, just out of curiosity, and it was not even a real phone number.  The fact that I can't see the real source of a message makes it difficult to block them effectively.  Is there a way to have a "safe" list instead of a "blocked" list for text messages -- in other words to block texting from everyone except my contact list?  It would be mind-bogglingly useful, and I suspect other users would welcome it as well.