title: Session.getActiveUser.getEmail() blank? Google sheets
body: <p>I want to check the user who is clicking that specific button. When I click on while signed in as my account it runs fine.
  but if anyone else runs it, it is blank. How can I get the logged user email id?</p>
  
  <p>This is my code:</p>
  
  <pre><code>function check_User(){
    var ui = SpreadsheetApp.getUi();
    var usr = Session.getActiveUser().getEmail();
    ss.toast(usr);
    if( usr == "abc@gmail.com" || usr =="myemail@gmail.com"){ 
  
      return true;
    }
    else{
      ui.alert("Not authorized");
      return false;
     }
    }
  </code></pre>