I think if you need to run your cron every 12 hours, may be this expression should work.

* 0,12 * * *

Try it out!

0 */12 * * *

in config.xml it not send mail every 12 hours.. can u say this is right expresion or not.. can u give me right expresion for every 12 hours cron set

I need to create a cron job in Magento which should send emails to customers whose order status is complete. I need to schedule this cron job such that it checks for order with status = “complete” and send them emails. Also the customers which are already sent an email should be marked so that they are not sent email twice.

I have created a custom module and in its config.xml I have added my template email and cron job scheduled.

Also in the Module>>Model>>Observer.php I have declared my sendEmail() trying to send a test email to my email id.

I try to run this cron task by running http://yourdomain.com/cron.php. But I fail to get any mail.

Any suggestions please?

<config>
  <!-- ... --->
  <global>
    <models>
      <birthday>
         <class>Inchoo_Birthday_Model</class>
      </birthday>
    </models>
  </global>
  <!-- ... -->
</config>

It is OK. The global section is important )))

With using the package ang module name of the example:

<config>
  <!-- ... -->
  <models>
    <birthday>
      <class>Inchoo_Birthday_Model</class>
    </birthday>
  </models>
</config>

It will eliminate the ‘invalid callback’ error mentioned above by Codep and cron will work.

What is role of crontab command on linux(CentOS 5.3)
and What is role of “cron.php” ?
and What is role of magento’s cron script ?

Have any relevant above three kind of task ?? please….

He’s been very kind and tried to help, but maybe you are the right person for this topic.
We are experiencing strange behavior with cron-based.
After the two comments in Toni’s blog, we re-queued the newsletter, launched cron via wget and are observing the mail server’s behaviour.
Current batch size ($countOfSubscritions) is 20.
Right after the cron run, the mail server received 105 e-mails for delivery.
How’s it that 20 becomes 105 with a single cron run?