how to send automatic emails from tomcat

[anand]

I have developed a web based time sheet management system. 
 
Now I want to add a new feature whereby every week on a given day and
time, it will check for a particular condition and if it is not
satisfied, it should send out automatic mails through my SMTP server. 
 
If anyone has any idea on this, please reply. 
 
Thanks,
Anand.