I need to create a program for sending Bulk News letter.I m planned to create a program which will send some mails(Suppose 20 mails) in between the interval of 30 seconds.I have written a PHP Program For that.My purpose is to create a crontab entry when administrator clicks the send Button.. For more clearly, When Administator Clicks on the "start sending button"(PHP SIDE) it should call a Perl File ,That PERL file create a Crontab Entry and adds into the crontab file at that instant only.When All the mails are send There is a status showing that No mails to send right now..At that Time administartor presses the "Stop" button, then it removes the crontab entry from the file.But i dont how to add a crontab entry in to the crontab file at a particular instant.I am requesting you to give me the slution as soon as early please. I am a New Bee in PERL..