What is a bad file and how do I open a bad file?

A BAD file is an Exchange Badmail File developed and released by Microsoft.  It usually entails email messages that Microsoft Exchange Server failed to deliver to prospective recipients mentioned in the email address.  The return email is composed of the sender’s email address, recipients email address, the body of the message and subject name.  It also explains the reason and circumstances why the email was not delivered and returned by the server.  Returned files or BAD files are normally stored in a folder called Badmail together with .BDR and .BDP files.  This can be viewed by simply transferring the said file to the Pickup folder.  One of the reasons why an email ends up as failed mail is when there is problem with the recipients email address.  The server might have had problems locating the email address or for the very reason that the mentioned email address does not exist or has ceased to exist.  A particular point noticed in this situation is error on the part of the sender of the message, which is an incorrect email address typed in the recipient text field.