php mail reminder with codeigniter

Hello, i want a module mail reminder with php and codeigniter, where admin panel is with login account and have privileges as admin panel, manager panel and user panel. The interface is like LTE Admin Panel. User interfaces admin panel: - user panel privileges. - can create accounts and set privileges. - can update and delete mails scheduled. - can add a list of mails for database, then when you want select where to send this mail users will be able to select how much people will receive this mail. - can check the next mails coming in list sorted by all or per account. manager panel: - can check the next mails coming in list sorted by all or per account. - user panel privileges. user panel: - after login he can add and check his next mails coming. The mail reminder: - user can write a email and set when this will be sended, this mail need to be sended three months before to the date configured. example: ---- I will have a renovation of contract the next 28 - july - 2018. then in MAY 28 i will receive a reminder via mail, then the same notification for two months, 1 month, 15 days, 7 days, 3 days and 1 day. Of course, if i renewed it i want the option to check "TASK ALREADY FINISHED" then this will remember the next coming year to the same date. pd: amazing theme is not needed, i know some coding and i want to set my own template and i want to understand the logic of this proyect. then please code all in english with some explanations because im student still. the reference in uploaded file is from e*reminder script