Automatic suppression of non-duplicate messages

[Eirik Byrkjeflot Anonsen]

Jani Nikula <jani at nikula.org> writes:

> On Sat, 03 Nov 2012, David Bremner <david at tethera.net> wrote:
>> Offhand I'm not sure of a good method of automatically deciding what is
>> the same message (with e.g. headers and footer text added by a mailing
>> list).
>
> Assuming there was good method, what would you do with two different
> messages that have the same message id? That is the unique id we use to
> identify messages (which should be fine per RFC 5322 and its
> predecessors; we're talking about messages from broken systems here).

We're also talking about data from "untrusted" sources.  Assuming that
such data is always non-broken seems overly optimistic.  (See
e.g. http://cr.yp.to/immhf/thread.html, the section "Security and
reliability issues" for one view on the matter.)

In fact, I'd say that it should be a design goal for any mail client to
deal with as much invalid input as possible.  Show big, fat warning
messages if you want to, but don't just drop the message and pretend it
does not exist.

eirik