Here are a few signs that despite "good" results, your email program is getting lapped: 

1. You rarely, if ever, A/B test anything.
2. You don't review performance metrics. 
3. You don't segment. 
4. Transactional messages are the only triggered emails that you send.
5. You haven't updated your sign-up form, opt-in confirmation page or any other such pages since launching them. 
6. You don't make it easy for customers to sign up for your emails. 
7. You're totally preoccupied with the day-to-day of getting emails out the door.