If you know what to look for, scam emails aren’t too difficult to spot. They’re usually written in broken English and may even mention the cliché of a Nigerian prince in need of money that’s so overused it’s become an internet-wide joke. The classic formula may feel like it’s run its course, but according to researchers, it’s even more effective now that more people recognize it.

In 2012, Microsoft Research released a paper [PDF] looking at why the Nigerian or “419” scam in particular has persisted over the years. They found that because such a large swath of internet users have been trained to recognize that certain scam, the small portion of people that do respond are more likely to ignore the red flags and send money.

While a craftier email may get the attention of more people, many of them would turn out to be “false positives” who cut contact with the scammer before handing over any cash. A consistently obvious email narrows down the pool of responders to the most gullible individuals—a.k.a. the people scammers are looking to target.

When you receive an email from a member of Nigerian royalty or someone else asking for money, sending it to your trash folder is often the best course of action. The author of Microsoft’s research paper, Cormac Herley, has a slightly different suggestion for victims of spam. When speaking with authors Steven D. Levitt and Stephen J. Dubner for their Freakonomics follow-up Think Like a Freak, he recommended gaming the system by engaging with scammers and wasting as much of their time as possible. For an idea of how that might play out, you can watch this TED talk where a comedian talks about doing just that.