How to trigger email in his outlook for user responsible for a particular task in IW22 task tab.

Hi Experts,

i have one requirement as mentioned below.

1.in the transaction IW22(PM notification change).

2.In  the task tab,when a user creats task ,he enters user responsible for that task .An email should be triggered to the user responsible for that                particular task in his outlook whenever he release or save the task.

currently i have implemented this requirement with user exit,but right now the mail is going to that person who has created that notification.It is not going to the user responsible for task.because in one notification we have more than one  task and different task can have different user responsible.

Please help me its urgent.