Google Apps Script for parsing entire gmail messages and save it into google spreadsheet

script.gs

// Google may setup some restrictions for a massive requests per seconds.
// So you need planning to run script multiple times
var SEARCH_QUERY = '!label:Parsed_by_Script';

// The Main func - entry point
function gmailExportToSpreadsheet(){
  // we
  for (var index = 0; index <= 2000; index += 100){
    parseEmailMessages(index);
    Logger.log("Parsed next %s messages.", index);
    Utilities.sleep(1000);
  }
}
 
function parseEmailMessages(start) {
  var sheetId, sheet, threads, labelName, label;
  
  labelName = 'Parsed_by_Script'; // label for already parsed threads
  // SheetId is your google spreadsheet id
  sheetId = '1r7Gb7fLbsiyPImzh4TqX9HWm6SThbcYAO2SsPIPBqOM'; // place id document here (from your browser address line)
  label = GmailApp.getUserLabelByName(labelName)||GmailApp.createLabel(labelName);

  sheet = SpreadsheetApp.openById(sheetId).getSheets()[0];
  var threads = GmailApp.search(SEARCH_QUERY, start, 100);
  
  for (var i = 0; i < threads.length; i++) {
    // Get the first email message of a threads
    var messages = threads[i].getMessages();
    for (var j = 0; j < messages.length; j++){ 
      
      // Get the plain text body of the email message
      // Note that for some types of messages getPlainBody() method may return null
      // in such cases consider using getRawContent() or getBody() methods and parse HTML
      var message = messages[j];
      var content = message.getPlainBody();
      if (content) {
        var date = message.getDate(),
          subject = message.getSubject(),
          sender_tmp = message.getFrom(),
          body = content;
        var tmp = sender_tmp.match(/<\s*([A-Za-z0-9_@.-]+)>/);
        var sender = (tmp && tmp[1]) ? tmp[1].trim() : sender_tmp.trim();
      
        sheet.appendRow([date, subject, sender, body]);
      }// End if
    }// End for j loop
    threads[i].addLabel(label); //add your label for parsed messages 
    //Utilities.sleep(2000);
  }// End for i loop
}