1. A method for determining a difference between a sent email and an edited email, comprising: detecting a user editing the sent email; activating a delta engine program in response to the detecting the user editing the sent email; determining whether there is a content difference between the sent email and the edited email upon the activation of the delta engine program, the content difference including a set of items, each item in the set of items indicating a difference between the sent email and the edited email; storing the content difference upon determining that there is the content difference; determining mapping instructions for each item in the set of items, wherein the mapping instructions specify position mapping instructions for integrating the content difference into the sent email; storing the mapping instructions; storing an email header; joining the content difference, the mapping instructions, the email header and also adding an update attribute to create a delta; and, sending the delta.