title: TypeError: app.post(...).then is not a function
body: <p>I am having some problems with my API routes in a node App. I switched the 'to' portion of my Nodemailer and now all of a sudden it is giving me problems with the Async in my 'Post' Action. </p>
  
  <p>I keep getting an error mesage: <strong>'TypeError: app.post(...).then is not a function'</strong></p>
  
  <p>Here is the code:</p>
  
  <pre><code>app.post("/api/applicants", function(req, res) {
    db.Applicant.create(req.body);
    res.send('Successfully posted new Applicant');       
    }).then(function(appPost){
        //mail details for nodemailer
        let mailOptions = {
            from: '"noreply@cap.org" &lt;app@cap.org&gt;', // sender address
            to: 'ijvv7dth54f7zp3w@ethereal.email', // list of receivers
            subject: 'Application Submitted', // Subject line
            text: req.body.firstname + ' ' + req.body.last_name + ' just sent you a message!', // plain text body
            html: '&lt;b&gt;'+req.body.first_name+'&lt;/b&gt;' + '&lt;/br&gt;' +
            ''  + req.body.last_name   + '&lt;/br&gt;' + 
            'DOB: ' 
             // html body
        };
        transporter.sendMail(mailOptions, (error, info) =&gt; {
            if (error) {
                return console.log(error);
            }
            console.log('Message sent: %s', info.messageId);
            // Preview only available when sending through an Ethereal account
            console.log('Preview URL: %s', nodemailer.getTestMessageUrl(info));
            // Message sent: &lt;b658f8ca-6296-ccf4-8306-87d57a0b4321@blurdybloop.com&gt;
            // Preview URL: https://ethereal.email/message/WaQKMgKddxQDoou...
        }); 
     });
  </code></pre>