“Please” and “thank you.” Being nice. Ending a note with “Yours sincerely” or “Best regards,” but not “Best wishes” for someone you don’t know personally.

Yes, most of the things customer-service agents need to know to keep customers happy they learned in grade school, according to a new study from customer-service platform provider Zendesk. It also turns out that “please” and “thank you” from customers indicate that the service is more likely to be rated as good.

Instead of its normal quarterly focus on operational efficiency metrics, this Zendesk study focuses on connections between behavioral clues and customer behavior.

The big takeaway is “always use your manners and treat people nicely and you’re probably going to end up happier,” Zendesk data-science lead Jason Maynard told VentureBeat. This applies, he noted, to both customers and agents.

A nice agent counts nearly as much for customers rating the interactions as “good” as having the problem itself resolved quickly, 65 percent versus 69 percent. But it turns out that “please,” “thank you,” and “sorry,” if repeated too much by agents, indicate the customer satisfaction will plummet because the conversation is going on too long – and the problem is probably not getting fixed.

Zendesk also decided to investigate “whether a customer who writes a War and Peace-length support request [i.e., trouble ticket] is more or less likely to end up happy with their customer service.”

Answer: less. Happy and satisfied customers don’t tend to spend time writing up long support requests.

Place is also an indicator. New Zealanders are commonly ranked among the happiest people on Earth, and that spills over into their generally high level of customer satisfaction.

Maynard pointed out to us that this is the first time Zendesk has correlated the country email domains of customers with their satisfaction level — and they tend to be consistent whether or not the customer service agent is operating from that country.

It may not be that companies providing customer service to New Zealand are any better at customer service, but that the customers there have lower expectations. Zendesk noted that France, sometimes characterized as being full of unhappy people, often scores in the lower third of customer satisfaction.

“But that doesn’t necessarily mean that French companies provide inferior service,” the report notes. “It could simply be the case that their customers have higher expectations of customer service, and tend to give lower satisfaction ratings.”