OT: To CC or not to CC? (was: Sorry for posting the same message twice)

[Christoph Groth <christoph@grothesque.org>]

Piotr Ożarowski wrote:

> your message went through, I simply decide to ignore you for a while
> because you CCed me on a mailing list that I subscribe :P

But how can I know that you, or someone else, is subscribed?  In this
particular case it's of course quite obvious, but I believe that instead
of asking oneself this question each time when replying to some message
on some mailing list, CCing the author by default is the only reasonable
policy.  People who are annoyed by receiving the same message twice can
quite easily configure any good MUA to hide messages that also go to
lists that they read anyway.