Event - Fire Supplier Delivery Reminder

Community,

We are going to utilize the IFS standard functionality “Purchase Order Delivery Reminder” to fire purchase order delivery reminders supplier based email to suppliers (RMB functionality) when new objects are created in this window. 

To automate this process, I think we better create a custom event. We are not quite familiar with Custom Event. Any help I could get from here? any document we could use?  

Thank you all.