under-promise and over-deliver

To avoid raising expectations in order to subsequently exceed them. Used as a strategy to ensure the satisfaction of one's client, customer, boss, etc. Also spelled without hyphens. I want all of our customer service representatives to under-promise and over-deliver, so that all experiences with our company are positive ones. The boss urges us to underpromise and overdeliver, but I think our clients are perfectly happy when we do just what we promised.