Mailback is a means of sending you the requested statement as a password protected and encrypted attachment to the email id registered in your account. If you did not register an email id at the time of opening your account, please write to us under the signatures of all the account holders. For obvious reasons we cannot accept email requests for registration of an email id into an existing account.
CAMS : https://www.camsonline.com/InvestorServices/COL_ISAccountStatementCKF.aspx