Q:

Difference between message headers: Content-Type: charset="UTF-8" and Content-Transfer-Encoding: 8bit

I had received some mail message, but I was confused with these headers:
Content-Type: text/plain;
    format=flowed;
    charset="UTF-8";
    reply-type=response
Content-Transfer-Encoding: 8bit

If Content-Type: charset="UTF-8" is already specified, so why we need Content-Transfer-Encoding: 8bit?

A:

Because you can also have:
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: base64
The charset is independent of the content encoding.

