Do you mean that if "Followup-To: foo" where foo is an e-mail
address would cause problems if it occurred in Netnews?
What kind of problems would it cause? What would happen?
Existing news-reading software typically assumes that the Followup-To
header conforms to RFC 1036, which does not permit mailing addresses
in that header. The software typically would misunderstand the address
as newsgroup name(s), and attempt to post the followup to news rather
than sending it as mail. Confusion and possible loss of the message
would ensue.
As I understand it, most header fields are the same in e-mail
and in Netnews, and the recipients of a message can be both
Newsgroups and e-mail recipients at the same time...
Most header fields are the same. However, newsgroup names and email
addresses are like oil and water: they do not mix. The headers which
contain newsgroups may not contain addresses, and vice versa. There
is no real provision for the possibility that a single message might
be both a mail message *and* a news article. The idea is not unrealistic,
but one must remember that there are two separate universes involved.
Headers developed for use in one -- such as Followup-To -- must not be
modified in incompatible ways for use by the other, if you wish to
comply with the conventions of both.
The netnews community does not use Reply-To to specify newsgroups for
responses; you should not use Followup-To to specify email addresses
for responses.
Henry Spencer at U of Toronto Zoology
henry(_at_)zoo(_dot_)toronto(_dot_)edu utzoo!henry