Blank page after form submission

I'm extending the external form. My form looks like this:
<form action="<?php echo $this->action('submit_form')?>" method="post">

where 'submit_form' is a function in the controller which sends an email. But when the form is submitted I get a totally blank white page.

Anyone know what's wrong? Thank you.

PS. If I use the controller code directly in the form file, everything works fine.

Ah, and I get this in the address after submission: ""

There are no error messages, no error logs, nothing.

View Replies:
linuxoid replied on at Permalink Reply
It's all right, stupid me, it was just a typo in a variable name. It all works fine.

Although I wonder why there was no error?
clocktower replied on at Permalink Reply
We have run into this issue if the SMTP Method is set to External SMTP Server under Dashboard > System & Settings > Mail > SMTP Method and the server is not properly configured to send and receive mail.