smtp seems to have stopped working

I have been using mandril to send emails. Today the connection to mandrill stopped working. I am getting this error:

PHP Warning: fsockopen(): unable to connect to smtp.mandrillapp.com:587 (Connection timed out) in /directory/

The port was checked and is not blocked. This happened right in the middle of sending out mail though this. Any idea what happened or how I can troubleshoot this?