I want to send reminding mail to clients who's work is incomplete and he/she(client) must do his work within 7 days and also I want to send email to remind client when his deposit getting $0.00 so do credit. This will done according to database values.
You can create a php script that can be run as a cronjob that will connect to the MySQL database and then send the reminder emails to the clients that you need to contact.