Email says Multiple Content-Type header - HIGH DANGER

I have gotten this on a couple of important emails that I really need. How can I get these emails? I am totally stumped.

Have you changed any of the Mail Shield, Expert Settings ?

This is strange as certain email, that which has a text or html parts to the email would have Multiple Content-Type header, so I would have thought that normal, see content type, http://en.wikipedia.org/wiki/MIME.

I went in under the expert, then clicked on the sensitive but I still can’t read the email. What am I don’t wrong?

Having clicked on sensitivity, what is it set on, High or Normal or Low ?

I have mine set on High and have never come across this before, though I don’t know if any of the emails I get are in multi-format, text/html as generally I only get one form or the other (text or html).

However, just checked one of my emails and it is multi-part and no issues with avast (see image extract of the email headers).

What is the origin of this email ?