One reason why we can feel overwhelmed at work, is that we don’t use triage enough.
Simple triage for unexpected client phone calls and emails:
If you can answer their question or address their issue in 5 minutes, deal with it now, preferably by phone.
If it is urgent deal with it now. Have a clear, tangible definition of what ‘urgent’ means. Don’t rely on the client’s perception.
If it’s not urgent and you genuinely have time to deal with it now (i.e. doing so won’t delay any other client’s work or eat into your rest time), deal with it now, preferably by phone.
Otherwise, schedule time to deal with it and schedule a call with them to give your response. It helps to keep an hour or so set aside every day to schedule these into. That way you can keep on top of the work generated, and be clear with your client when they can expect an answer.
Every customer has top priority. That needs managing.