Or link them to a page with a POST form that actually performs the action. That way you only add a single click to the flow, and no remotely sane software will automatically perform POST requests to arbitrary urls.
I'm not a web developer. Out of curiosity, why is that?
These assumptions are so baked into web software that while assuming a GET request won't do anything zany or overly stateful is probably fine, assuming the same for a POST request should probably be considered negligent.