Forward Gmail to HTTP with Google Apps Script

gmail2http.js

// Simply run Install function once to setup.
// The following script does send HTTP requests for each unread email from any sender with the email domain '@domain.com'.
// The emails are processed in chronological order, from the oldest to the newest.
// This script is implemented with Single Instance Locking to prevent duplication.
// This script is implemented with Execution Timeout to prevent the execution time limit from being exceeded.

function Install () {
  Uninstall();
  ScriptApp.newTrigger('Run').timeBased().everyMinutes(1).create();
}

function Uninstall () {
  for (const trigger of ScriptApp.getProjectTriggers()) {
    if (trigger.getHandlerFunction() === 'Run') {
      ScriptApp.deleteTrigger(trigger);
    }
  }
}

function isInstalled () {
  let installed = false;
  for (const trigger of ScriptApp.getProjectTriggers()) {
    if (trigger.getHandlerFunction() === 'Run') {
      installed = true;
      break;
    }
  }
  return installed;
}

function Run () {
  const startTime = new Date();
  const lock = LockService.getScriptLock();
  try {
    if (lock.tryLock(100)) {
      if (!isInstalled()) {
        Install();
      }
      let index = 0;
      let threads = [];
      let olderThreads = [];
      do {
        olderThreads = GmailApp.search('is:unread from:(@domain.com)', index += olderThreads.length, 500);
        threads = threads.concat(olderThreads).slice(-100);
      } while (olderThreads.length === 500);
      (() => {
        for (const thread of threads.reverse().slice(0, 100)) {
          for (const message of thread.getMessages()) {
            if (new Date() - startTime < 300000) {
              message.refresh();
              if (message.isUnread()) {
                message.markRead();
                if (message.getHeader('Authentication-Results').split(';').map((line) => line.trim().split(' ')[0]).slice(1).every((check) => check.endsWith('=pass'))) {
                  UrlFetchApp.fetch('https://...', {
                    method: 'POST',
                    payload: {
                      from: message.getFrom(),
                      subject: message.getSubject(),
                      body: message.getBody(),
                      plainBody: message.getPlainBody(),
                      timestamp: message.getDate().getTime()
                    }
                  });
                }
              }
            } else {
              return;
            }
          }
        }
      })();
    }
  } finally {
    lock.releaseLock();
  }
}