MailSnitch

MailSnitch is an app that allows you to see who have watched your mails! Its a tracker for your mail, that helps you to know if people are just ignoring you, or if you've sent a secret mail, to see if it has been transfered to others! MailSnitch allows you to see the watchers IP, Operating System,Browser,City, and Country. If the user has seen your mail, you can also know if it was from Gmail, or any other mailing client.