A method for determining user uniqueness in e-mail campaigns. An instruction set is placed in an e-mail to form a modified e-mail. The modified e-mail is sent to a server for a distribution list, wherein the instruction set is executed in response to the modified e-mail being opened, wherein the instruction set identifies a reader of the modified e-mail based on an e-mail address of the reader and sends information to a collection device about the modified e-mail and an identification of the reader that opened the modified e-mail.