What is Communications Data?

[Ken Brown]

Watkin Simon wrote:

> Here's the header for your e-mail.  Where - other than the subject line - is
> the content?

Even using the common-sense idea of content as "stuff that the
originator put in" most email headers are content. The standard is
screwed and things like:

> To: ukcrypto@chiark.greenend.org.uk
> From: Ian Miller <Ian_Miller@singularis.ltd.uk>
> Subject: Re: What is Communications Data?
> Cc: ukcrypto@chiark.greenend.org.uk
> Reply-To: ukcrypto@chiark.greenend.org.uk
> Sender: ukcrypto-admin@chiark.greenend.org.uk
> Errors-To: ukcrypto-admin@chiark.greenend.org.uk

*look* like routing data, but are in fact comments inserted by the
originator, through whatever email client they choose to use.