These can be applied to verbal, written, remote, local, +other, etc., kinds of communication.
1. Wait / pause 1-2 seconds / breaths before responding.
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2. When angry, wait a minimum of 24 hours before responding - and let the other party know that's what you're doing, and why, if they are reasonably expecting a response sooner.
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Look for physical cues such as elevated heart rate, perspiration, etc.