How to get "Send e-mail when ownership is assigned?" functionality on a Non Issue Tracking or Task list?

I have created a Custom SharePoint list and I want to be able to add the ability to send an e-mail to the person who the list item is assigned to just like the Issue Tracking and Task lists do.

How can I enable this functionality on an existing list with lots of data populated in it?

From serverfault ObligatoryMoniker

• This is easy to do in Sharepoint Designer.

  Just create a workflow assigned to the list. (either have it start when the item is created or when it is changed, or both). Create a column - Assigned Owner

  The logic you use in your workflow is up to you depending on if the assigned owner will change.

  EG create a column (Assigned Owner) add logic that if this field is not blank then.. ... then add action Send an Email.. (choose workflow lookup and send it to the assigned owner field)..put what you want in the field and title - then close the workflow..

  ObligatoryMoniker : Your recommendation gets the job done but introduces overhead that I would like to avoid. I am really looking to be able to enable the base functionality built in to SharePoint, not add something additional.
  From Lynchy

• The only true solution we have found to this has been to write a custom C# application that allows us to copy all list items from an existing custom list into an issues list so that we now have the e-mail on assignment functionality.

  From ObligatoryMoniker