Can't send or receive email

Please help ASAP. Since yesterday, I cannot send or receive email. People are telling me their emails to me are bouncing back. When trying to send, I get this message:

Your message did not reach some or all of the intended recipients.

      Subject:    test

      Sent: 10/24/2014 10:27 PM

The following recipient(s) cannot be reached:

 

      'Patty Bates-Ballard' on 10/24/2014 10:27 PM

            550 Administrative prohibition