Hello Pankaj,
I suppose you need to trigger mails each time the status changes.Please correct me if I understood it wrongly.
To trigger mails depending on user status condition , you can follow the steps mentioned in this link
http://scn.sap.com/people/dolores.correa/blog/2007/09/18/sending-e-mail-from-support-message
Kindly revert in case you have issues following it.
Regards,
Jinesh Jayan