Cross-posting should be limited to a small number of
directly related groups. You can cross-post your message to more than one newsgroup
if your message is relevant to more than one group. Cross-posting is easy to
do, and similar to sending email to more than one person. Simply
put a comma
between each newsgroup name you wish to post to in the address field.
However, remember that excessive cross-posting is considered bad form without
a good reason, because it multiplies the traffic on the Internet several times
without adding any new content. In the extreme case, if everybody cross-posted
every message to every group, then every group would look exactly the same!
You should cross-post only when really needed, and usually not to more
than three groups. All cross-posted groups should be closely related.
It is considered very bad form to cross-post a message to unrelated
groups, and could cause you to receive a large number of complaints
Because cross-posting of commercial advertisements has become a problem,
some news servers will ignore any message cross-posted to too many groups
-- depending on their configuration, somewhere between five and fifteen
is the usual limit.
When you cross-post an article to more than one group, you may want to specify
that all responses should be directed to a single group. If your software supports
it, this is done with a "Followup-To" header that specifies the group that all
replies should be directed to. If you set such a header, it is also considered
polite to mention that fact in your message, with a statement something like the
(Followups redirected to alt.misc.thoughts)