For some reason today we have numerous users sending email outbound reporting that they will get a bounce back stating that the email is being blocked due to AntMalware. WARNING: You tried to send a potential virus or unauthorized code
The Email Security service detected a potential virus or unauthorized code (such as a Trojan or Phish) in an email sent by you.
Possible MalWare 'Exploit/Link-b24a' found in "Attachment"
Exploit/Link-b24a seems to be common in each of the bounce back emails and logs