When you make a purchase through PayPal, the payment company sends you an email receipt with the details of the transaction. The Google script will scan your Gmail mailbox for all Paypal receipts, extracts the details from the message body using regex and saves them in a Google Spreadsheet for quick reference. The script extracts the transaction ID, the item purchased, the shipping cost and other details.

Also see: Sell Digital Goods with Paypal and Google Drive

function searchGmail() {
  var threads = GmailApp.search("from:paypal", 0, 10);

  var sheet = SpreadsheetApp.getActiveSheet();

  var header = sheet.getRange(1, 1, 1, sheet.getLastColumn()).getValues()[0];

  for (var t = 0; t < threads.length; t++) {
    var msgs = threads[t].getMessages();

    for (var m = 0; m < msgs.length; m++) {
      var response = extractPayPalDetails_(msgs[m]);

      var row = [];

      for (var h = 0; h < header.length; h++) {
        if (header[h] in response) {
          row.push(response[header[h]]);
        } else {
          row.push("");
        }
      }

      sheet.appendRow(row);
    }
  }
}

function extractPayPalDetails_(msg) {
  var result = {};

  var body = msg.getPlainBody().replace(/\s+/g, " "),
    html = msg.getBody().replace(/\s+/g, " ");

  var match = /[A-Z]{3}\s\d+,\s\d{4}\s\d{2}:\d{2}:\d{2}\s.{9}/g.exec(body);
  if (match) result["Transaction Date"] = match[1];

  match =
    /.*?>(.*?)<\/td>.*?>.*?>(.*?)<\/a><\/td>.*?>(.*?)<\/td>.*?>(.*?)<\/td>.*?>(.*?)<\/td><\/tr>/g.exec(
      html
    );
  if (match) {
    result["Item #"] = match[1];
    result["Item Title"] = match[2];
    result["Quantity"] = match[3];
    result["Price"] = match[4];
    result["Subtotal"] = match[5];
  }

  match = /Shipping & Handling:\s+\(.*?\)(.*?)\s+Shipping/g.exec(body);
  if (match) result["Shipping and Handling"] = match[1];

  match = /Shipping Insurance.*?:(.*?)\s+Total:\s*(.*? .*?)\s+/g.exec(body);
  if (match) {
    result["Shipping Insurance"] = match[1];
    result["Total"] = match[2];
  }

  match = /credit card statement as "(.*?)".*?purchased from:(.*?)\s+Receipt id:([\d\-]+)/gi.exec(body);
  if (match) {
    result["Name in Statement"] = match[1];
    result["Purchased From"] = match[2];
    result["Receipt ID"] = match[3];
  }

  match = /international shipping.*?Total:(.*?)\s+.*credit card statement as "(.*?)"/gi.exec(body);
  if (match) {
    result["International Shipping Total"] = match[1];
    result["International Name in Statement"] = match[2];
  }

  return result;
}