Not replying can be an answer. Sometimes the clearest message is the one you never type.

Silence communicates, and in some situations it is the cleanest thing available: no argument to continue, no new material to work with, nothing to misread on purpose. There are exchanges where any reply, however careful, only extends them. Choosing not to answer is a decision rather than an avoidance.

Tell the difference honestly before you use it. With somebody who deserves a response, silence is unkind and a short answer is better. With somebody fishing for a reaction, let the message sit and go do something else.