Do you have Policy on Performance Appraisal (PA) well in place? If yes, then why are you required to send this mail? Under the provisions of this policy, Team Leaders or their Managers are expected to know whose PA is to be done, when it is to be done and on what parameters it is to be done. It is they who are expected to send the mail without prodding.
In case if you do not have policy on PA, then it is high time you create one immediately. In this policy, create a complete timetable of activities.
Earlier I have given my reply on PA, you may click the following link to refer it:
From India, Bangalore