GoogleApps script using simple js to perform regexp searches.

GmailAppRegexpSearch.js

function GmailAppRegexpSearch ()
{
  var sheet   = SpreadsheetApp.getActiveSheet();
  var row     = 2;

  // Clear existing search results
  sheet.getRange(2, 1, sheet.getMaxRows() - 1, 4).clearContent();

  // Which Gmail Label should be searched?
  var label   = sheet.getRange("F3").getValue();

  // Get the Regular Expression Search Pattern
  var pattern = sheet.getRange("F4").getValue();

  // Retrieve all threads of the specified label
  var threads = GmailApp.search("in:" + label);

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

    for (var m = 0 ; m < messages.length ; m++)
    {
      var msg = messages[m].getBody();

      // Does the message content match the search pattern?
      if (msg.search(pattern) !== -1)
      {
        // Format and print the date of the matching message
        sheet.getRange(row,1).setValue(
          Utilities.formatDate(messages[m].getDate(),"GMT","yyyy-MM-dd")
        );

        // Print the sender's name and email address
        sheet.getRange(row,2).setValue(messages[m].getFrom());

        // Print the message subject
        sheet.getRange(row,3).setValue(messages[m].getSubject());

        // Print the unique URL of the Gmail message
        var id = "https://mail.google.com/mail/u/0/#all/" + messages[m].getId();
        sheet.getRange(row,4).setFormula('=hyperlink("' + id + '", "View")');

        // Move to the next row
        row++;
      }
    }
  }
}