What does "WARNING: UNSCANNABLE EXTRACTION FAILED" in a scheduled report subject mean?

Environment:

All sites, Reports, Scheduled reports

Issue:

A scheduled report has a notification like "[WARNING: UNSCANNABLE EXTRACTION FAILED]" in subject when an email is received, but is not part of the scheduled report's subject. 

Resolution:

This warning comes from outside  Oracle B2C Service, and is appended by one of the mail servers that handle the email.  For example, "WARNING: UNSCANNABLE EXTRACTION FAILED" is something that is sometimes added on by the recipient's mail server and it is usually from a firewall or anti virus system that is trying to scan the incoming email attachment before delivering it to the recipient mailbox. This occurs when reason it cannot scan the attachment, so appends this message to the subject line as a notification of such a failure. 

You can test to confirm that this is the cause by adding an external email address (for example a gmail address) to the schedule. After doing so check to see if the subject the email received on the gmail address contains the same warning notification. If it does not, that will confirm that this warning came from the receiving mail server.