This could be rightfully construed as a beginner's question.
Consider the following e-mail header:
MIME-Version: 1.0
My Questions:
EDIT: Is it true that whenever you specify a 'Content Type' header, no matter what that content type happens to be, that you should also specify 'MIME-Version'? [This link tipped me off to the possibility.]
According to Wikipedia, you should use the 'MIME-Version: 1.0' heading when you're sending an e-mail that contains one of the following: