Your bookkeeper gets an email. It’s from you — your name, your address, sounds just like you. “Hey, we’re switching banks for the Henderson payment. New account info attached, can you send it today? Slammed, can’t talk, just handle it.” She sends the wire. $18,000. Gone. It wasn’t you. It was never you.

This is called business email compromise, and it’s not some rare thing that happens to big companies. Small shops are the favorite target, because the crook knows you don’t have an IT guy double-checking. The FBI says it’s stolen over $50 billion — with a B — mostly from regular businesses like yours.

Here’s the whole defense, and it costs you nothing:

Any time money moves or bank details change — pick up the phone and call the person. Using the number you already have. Not the number in the email.

That’s it. That’s the fix. The crook can fake an email all day long. He can’t answer your bookkeeper’s call to the cell number she’s had for six years. One phone call kills this entire scam.

Make it a rule out loud, this week: “We don’t wire money or change payment info off an email. Ever. We call first.” Say it to whoever touches your money. That one sentence is worth more than any software you could buy.

Next week: the two-minute change that locks down your email so the crook can’t get in to send that fake message in the first place.