When I setup a Content filtering rule in Mail security it is only replacing part of the message with the replacement text. I'm not sure why this is happening, it is trying to quarantine all of the correct emails.
The rule i have setup just checks for specific words within the body of the email by using a match list. It is set to quarantine the message and replace the body of the message with a message explaining what has been done. It seems to only replace the first part of the text, and the rest is still forwarded onto the user.