[Exim] Marking the authenticated SMTP-User in the Header?

Hi all,

first of all: Thanks Phil, for exim. I really like it: No mailer is that
flexible and still that easy to use like your exim is. Last year it
nearly safed my life since it finally alowed me to stay within a
deadline because of it being so easy to do even advanced things with it.

My question: Yesterday I finally had the time to enable SMTP-AUTH using
my MySQL user Database (there was not possility to use the server for
realying before: It's mainly a webmail-service). I had no problems
setting it up and it works well.

One question though: Is it possible to add the authenticated user that
sent the message somewhere to the header? I mean something like
"X-Real-User: <<username that was used when authenticating>>" or
something else? Finally this would help me and the recipients tracking
users abusing the SMTPAuth-Service.

It's now quite a long time I last read the whole manual, so possibly
it's documented somewhere, but I don't really know where I would have to
search and I do not currently have the time to re-read the whole manual.

Many thanks

Philip
PS: Yesterday, I finally pre-ordered the book. Phil: Do you have an idea
when it is going to be delivered?