Gov.uk under Corresponding with HMRC by email says to use email for HMRCto contact you, one needs to confirm by email acceptance of the risks of using email etc. Neither HMRC nor Gov.UK websites advise Gov or HMRC email address to which this acceptance need to be conveyed. More so in case if an individual is not in UK how does one convey that acceptance of risks for using email. The individual's email is already registered with HMRC under Gov Gateway.