When open up the header or read the raw source of an email, I see header-vales in, for example,
Thread-index to be strings of encoded text. I though they are base64 but I tried converting them with online base64 decoder and didn't work, saying the string of text is not base64 encoded. I also tried decode in BinHex - no luck either.
I though MIME headers are either base64 or BinHex, but neither decoding results in readable text.
How can I decode these header-values to english?