Setting Up Cron For Post By Email Pro Options

[Webfooted]

Hi there

I've purchased a copy of Post by Email Pro to use with Kunena. I'm struggling to get the Cron set up correctly. I have tried two methods:

1. Setting up a cron job directly as follows:
/usr/bin/php5 -q /home/sites/wfdevelopment.co.uk/public_html/irms201308/administrator/components/com_post_by_email/cron.post_by_email.php >> /dev/null
I've checked the file path is correct with my web hosts. This outputs the following:
PHP Warning: session_start() [<a href='function.session-start'>function.session-start</a>]: Cannot send session cookie - headers already sent in /home/sites/wfdevelopment.co.uk/public_html/irms201308/libraries/joomla/session/session.php on line 532
PHP Warning: session_start() [<a href='function.session-start'>function.session-start</a>]: Cannot send session cache limiter - headers already sent in /home/sites/wfdevelopment.co.uk/public_html/irms201308/libraries/joomla/session/session.php on line 532

2. Creating the mycron.php file with the following cron job:
/usr/bin/php5 -q /home/sites/wfdevelopment.co.uk/public_html/irms201308/mycron.php >> /dev/null
This gives the following output:
PHP Warning: file_get_contents(http://www.wfdevelopment.co.uk/irms201308/administrator/components/com_post_by_email/cron.post_by_email.php) [<a href='function.file-get-contents'>function.file-get-contents</a>]: failed to open stream: Connection refused in /home/sites/wfdevelopment.co.uk/public_html/irms201308/mycron.php on line 2

Can you advise me what I'm doing wrong please?

Joomla: 2.5.8
Post By E-Mail: 1.8.0

Cheers, Emily