Parse the string of recipients returned by Gmail into raw email addresses. For example, if Gmail provides a recipient string in form of `George Washington <gwashington@potus.com>`, this function will return `gwashington@potus.com`

getRawEmail.js

/**
 * Parse the string of recipients returned by Gmail into raw email addresses.
 * For example, if Gmail provides a recipient string in form of
 * "George Washington <gwashington@potus.com>"
 * this function will return
 * "gwashington@potus.com"
 * @param {string} gmailRecipients String of comma-separated recipients returned by GmailMessages.getTo(), .getCc(), or .getBcc()
 * @returns The raw email addresses of gmailRecipients, without recipient name and angle brackets
 */
function getRawEmail_(gmailRecipients) {
  var regexp = /<([^\>]+)>/;
  return gmailRecipients.split(',').map(recipient => {
    let matchResult = recipient.match(regexp);
    if (!matchResult) {
      return recipient;
    } else {
      return matchResult[1];
    }
  }).join(',');
}