将HTML传递给PHP参数?

I need to pass HTML to the following function

$response = good_mail_using_mandrill($to,$subject,$body,$from_name,$from_email,$MandrilluserAPIKey,$SubAccountID );

At the moment $body takes the entire HTML content from a MySQL field and sends the API call to Mandrill.

What I find is that certain HTML goes through but others dont. I am not sure what tags in the HTML cause this failure. Are there any restrictions on what content can be sent in the $body variable?

This is driving me nuts. Mandrill says that they are receiving "null" content.

Is there a way to read the API call at delivery?