What will you do if you called the wrong number and/or sent the wrong message?

There were a few times when I called a wrong number or wrong message because these days, a lot of people use their smartphones to call or to chat and I do. Comparing to call, I often make the mistake to sending a wrong e-mail during my working like sending an e-mail to the wrong person or sending accidently a confidential file that should not be sent. In those case I will use the ‘collect back’(?) function of the e-mail program as soon as I notice that. If the receiver does not read the e-mail yet, I can collect back that mail fortunately but if the receiver read already, I cannot! In that case, I will apologize and admit my mistake frankly and then ask to delete the file politely and desperately.