The messages that cause the most damage are almost never the ones people planned to send. They are written in about ninety seconds.
A message arrives that feels unfair. The reply is composed immediately, while the reaction is at its strongest, and sent before the reaction has faded.
An hour later most people would have written something different. By then it is a record.
In an ordinary argument the words disperse. In co-parenting the exchange is typically written, retained, and readable later by people who were not present — including, in some circumstances, a court.
The angriest thirty seconds of a difficult year can end up representing you.
You are not only having a conversation. You are creating a document, and you do not control who reads it later.
Not restraint, which is exhausting and unreliable. Time.
Write the reply. Do not send it. Look at it after an hour, or the next morning if the subject is not urgent. The vast majority of messages people regret would not survive that gap.
Answer only the logistical question. Schedule, time, place, arrangement.
Leave the characterisation, the history, and the response to the tone. Those never resolve anything in writing and they always end up in the record.
Something involving the child's immediate safety or a change happening within hours. Those need an immediate answer.
Almost nothing else does, and treating everything as urgent is what produces the messages people regret.
Do not send five more explaining it. A short, plain correction is better than an escalating thread, and the thread is what does the damage.