Getting this error message on yellow bar on top of every email "The email below might contain script or content that is potentially harmful and has been blocked."

Hello,

I am getting this error message on yellow bar on top of every email "The email below might contain script or content that is potentially harmful and has been blocked."

Already under Administration -> Site Settings -> Email -> Use secure frames to restrict e-mail message content is set to No.

The email content is plain text no  html content inside .

Please advice .