async await syntax doesn't work

[websocket98765]

Just a heads up that this doesn't send email successfully when using async/await syntax. The code runs through as if it succeeded (doesn't throw an error), but the email is not sent and result logs as undefined.

  try {
    const result = await client.send(message);
    console.log('Email sent successfully', result);
  } catch (err) {
    console.error(err);
  }

The callback style in the docs works, of course.

  client.send(message, (err, message) => {
    if (err) {
      console.error(err);
    } else {
      console.log('Email sent successfully', message);
    }
  });

But it might be good to support both.

[zackschuster]

the current version of the library is (mostly) written in the old "errback" style, so for now the recommendation is to use util.promisify and/or custom Promise wrappers for async/await workflows.

i'm not opposed to switching to a Promise-based interface in a future release. definitely open to a PR for this.

[zackschuster]

code snippet for util.promisify with async/await:

const client = new SMTPClient({});
// bind necessary to retain internal access to client prototype
const sendAsync = util.promisify(client.send.bind(client));

try {
  const result = await sendAsync(message);
} catch (err) {
  // handle err
}

[eleith]

thanks @zackschuster lgtm