Send an email notification when item is delted from sharepoint custom list

when you set up an alert there is the option to send automatic alert when item is deleted. This is by far the easiest and fastest way to achieve what you want.

You can achieve this functionality using SharePoint Event Receiver.

SPItemEventReceiver.ItemDeleted is method that Handles the asynchronous event that occurs after an item is deleted. You can write your Send email notification code/logic in this method.

Link for How to Create event receiver :

https://msdn.microsoft.com/en-us/library/ee231563.aspx

http://beginnersbook.com/2013/02/event-receivers-in-sharepoint/

Please try to implement this way.