What is Communications Data?

[Ian G Batten]

On Sun, 10 Nov 2002, Charles Lindsey wrote:

> 	On Sat, 9 Nov 2002 21:57:44 +0000
> 	Andrew McLean <andrew@at-andros.demon.co.uk> said...
> 
> > The analogy of the letter in the envelope is obvious. Some of the 
> > information on the letter could be used to identify the sender or the 
> > recipient of the letter. However, assuming the envelope is correctly 
> > addressed, the Royal Mail don't need to open the envelope to make the 
> > delivery. Surely traffic data should be restricted to information that 
> > is actually used in operating the communications system.  Of course in 
> > the electronic world these lines get a bit blurred.
> 
> Yes, but if they are unable to deliver it they will open it in the hope
> of finding an address to 'bounce' it to. So in the email case, that is a
> choice between Return-Path or Reply-To.

In SMTP land, Return-Path: is typically only used by final delivery
agents to take the envelope MAIL FROM: and place it somewhere that the
end recipient can get at it.  It has no formal status as a header.

ian