how do I detect email snooping software?

Hi

 

I think my boyfriend may be reading my emails on my laptop by a spying program he may have installed on it while I was not around.

 

He mentioned once a long time ago his friend had such a program.

 

How do I scan for these types of hidden programs? 

 

Does my norton internet security  scan for these email spy programs?

 

And if someone installs a spy program while I am logged in but not around, I think norton will assume it is a safe program, so how do I identify that program if it hides itself?

 

Thanks for your help.