The time comes upon every public man when it is best for him to keep his lips closed.

Knowing when to stop talking is a skill that arrives late for most people. There are moments when anything you add makes it worse: when you have already been heard, when the other person is not ready, when the only thing another sentence achieves is to make you feel better. Silence in those moments looks passive and is not.

Before sending the reply that finishes an argument, ask what it would change. If the answer is only that you would feel more correct, that is the signal. Restraint is far cheaper than the retraction, and nobody regrets the sentence they did not send.