Check the raw email body and see if it consists of multiple encoded MIME parts. I'm seeing some spammers sending the message body as one part of innocuous conte

Check the raw email body and see if it consists of multiple encoded MIME parts. I'm seeing some spammers sending the message body as one part of innocuous content but then a different part is displayed when you open the email. I'm guessing this confuses the spam filter enough to let it through.