How to read email headers?

Can someone please point me to where I can find a complete reference to email headers (Da开发者_如何学编程te, From, To, Sender, etc.), if there is one?

The core header fields are described in RFC 5322. Futher header fields of MIME are described in RFC 2045 (general headers), RFC 2046 (media types), and RFC 2047 (non-ASCII text).

Might i recommend wikipedia's extensive article on the subject? The RFC's in the article should answer any questions you may have.

http://en.wikipedia.org/wiki/Email#Message_format

The full specification can be found in RFC822 or (more recent) in RFC2822.