nodemailer doesn't stop sending mails - node.js

Question

I have a simple nodemailer setup that sends emails without a problem. The only thing I can't figure out is how to stop it from sending once it started. I click send, it sends an email but the page keeps loading and soon I receive another email etc. Surely it should only send one email and close the process.
Can anybody see something I'm doing wrong here?
var smtpTransport = nodemailer.createTransport('SMTP', {
host: 'mail.francotanzarella.com',
secureConnection: false,
port: 587,
auth: {
user: 'contact#francotanzarella.com',
pass: '***'
}
});
app.post('/contact', function(req, res) {
var htmlTpl = '<h4>Message from' + ' ' + req.body.name + '</h4><p><span>' + req.body.email + '</span</p><p>' + req.body.message + '</p>';
mailOptions = {
from: 'noreply#francotanzarella.com',
to: 'contact#francotanzarella.com',
subject: 'New message from francotanzarella.com',
html: htmlTpl,
debug: true
}
smtpTransport.sendMail(mailOptions, function(error, response) {
if(error) {
console.log(error)
} else {
console.log(response.message);
}
smtpTransport.close();
});
});
contact.ejs
<form id="contact-form" method="POST" name="userForm" action="/contact" ng-submit="submitForm(userForm.$valid)" novalidate>
<div class="row">
<div class="small-12 column">
<div class="row" ng-class="{ 'error' : userForm.name.$invalid && !userForm.name.$pristine && submitted }">
<div class="small-12 column">
<label for="name" class="inline">Name</label>
</div>
<div class="small-12 column">
<input type="text" id="name" name="name" placeholder="Your name" ng-model="name" required />
<small class="error" ng-show="userForm.name.$invalid && !userForm.name.$pristine">Please enter your name</small>
</div>
</div>
<div class="row" ng-class="{ 'error' : userForm.email.$invalid && !userForm.email.$pristine && submitted }">
<div class="small-12 column">
<label for="email" class="inline">Email</label>
</div>
<div class="small-12 column">
<input type="email" id="email" name="email" placeholder="Your email" ng-model="email" required />
<small class="error" ng-show="userForm.email.$invalid && !userForm.email.$pristine">I need a valid email please</small>
</div>
</div>
<div class="row" ng-class="{ 'error' : userForm.message.$invalid && !userForm.message.$pristine && submitted }">
<div class="small-12 column">
<label for="message" class="inline">Message</label>
</div>
<div class="small-12 column">
<textarea id="message" name="message" placeholder="Send me a message" ng-model="message" required></textarea>
<small class="error" ng-show="userForm.message.$invalid && !userForm.message.$pristine">What? No message?</small>
</div>
</div>
<div class="row">
<div class="small-12 column">
<button type="submit" class="button" ng-disabled="userForm.$invalid">send</button>
</div>
</div>
</div>
</div>
<div id="form-response-container">
<div id="for-response-inner">
<h3 id="form-response"></h3>
</div>
</div>
</form>

Answer 1

Okay I fixed this. Not sure if it's the correct method but it works. I basically pass the browser a ok (200) when the email was sent successfully.
if(error) {
res.send(500);
} else {
res.send(200);
}