Ballew Kinnaman answers this pretty well -

> so... why isn't there a command i can issue which
> would delete everything sent to the list from that address?

My guess is that you probably could write an editor macro or perl script
that would do it: it would be complicated, but not difficult.  The real
problem is this:

> The whole idea of mailing list archives is to preserve
> what is said, not make the logs into personal swiss
> cheese at the whim of any random participant.
>
> My welcome messages make it clear that, if you speak
> (write) to the group, that message is before the group,
> permanently, as part of the archive.

This is a good idea; it's also a good idea to refuse to go through the
hassle of poking holes in archives on people's whims.  I had one case
where a woman was pretty sure her husband was going to lose his job if I
left a posting public, and I finally was persuaded, in that case, to
hold the list and kill the posting.  But even then, as I pointed out to
her, Pandora was well and truly out of the box: 750 people had read the
message, and some of them had certainly saved it.

-- Russ

St. Thomas University
http://www.stu.ca/~hunt/