You can update the mobile number & e-mail ID in your Demat Account through the modes mentioned below:
Log in to your linked ICICI Bank Internet Banking > Investments and Insurance > Demat > Service Requests > Demat > Updation of Mobile No., Telephone No. and e-mail ID
Call our Customer Care, authenticate the call entering the Demat Account number and TPIN or Debit Card number and PIN, so that the officer can raise a request to update e-mail ID in the Demat Account.
To know the local Customer Care numbers,  please click here.
Visit the nearest Demat enabled branch and fill the Form for E-mail Id/Mobile Number/Income Range Update Form for Individuals or Non-Individuals