s-o-1036 June 1994

10.4. Mail to and from News

Gatewaying mail to news, and vice-versa, is the most obvious
form of news gatewaying.  It is common to  set  up  gateways
between news and mail rather too casually.

It  is hard to go very wrong in gatewaying news into a mail-
ing list, except for the non-trivial matter of  making  sure
that  error  reports  go  to the local administration rather
than to the authors of news articles.  (This requires atten-
tion  to  the  "envelope  address" as well as to the message
headers.)  Doing the reverse connection  correctly  is  much
harder than it looks.

     NOTE: In particular, just feeding the mail message
     to "inews -h" or the  equivalent  is  NOT,  repeat
     NOT,  adequate  to gateway mail to news.  Signifi-
     cant gatewaying software is  necessary  to  do  it
     right.   Not  all headers of mail messages conform
     to even the MAIL specifications,  never  mind  the
     stricter rules for news.

It  is  useful to distinguish between two different forms of
mail-to-news gatewaying: gatewaying a mailing  list  into  a
newsgroup,  and  operating a "post-by-mail" service in which

INTERNET DRAFT to be        NEWS                   sec. 10.4


individual articles can be posted to a newsgroup by  mailing
them  to a specific address.  In the first case, the message
is already being  "broadcast",  and  the  situation  can  be
viewed  as  gatewaying  one  form of news into another.  The
second case is closer to that of a moderator posting submis-
sions to a moderated newsgroup.

In  either  case,  the discussions in the preceding two sec-
tions are relevant, as is the Hippocratic Principle of  sec-
tion  9.   However,  some additional considerations are spe-
cific to mail-to-news gatewaying.

As mentioned in section 6, point-to-point  headers  like  To
and  Cc  SHOULD  not  appear as such in news, although it is
suggested that they be transformed to "X-" headers, e.g.  X-
To  and X-Cc, to preserve their information content for pos-
sible use  by  readers  or  troubleshooters.   The  Received
header  is  entirely  specific to MAIL and SHOULD be deleted
completely  during  gatewaying,  except  perhaps   for   the
Received header supplied by the gateway host itself.

The  Sender  header is a tricky case, one where mailing-list
and post-by-mail practice  should  differ.   For  gatewaying
mailing  lists, the mailing-list host should be considered a
relayer, and the From and Sender  headers  supplied  in  its
transmissions left strictly untouched.  For post-by-mail, as
for a moderator posting  a  mailed  submission,  the  Sender
header should reflect the poster rather than the author.  If
a post-by-mail gateway  receives  a  message  with  its  own
Sender  header,  it might wish to preserve the content in an
X-Sender header.

It will generally be necessary to transform  between  mail's
In-Reply-To/References convention and news's References/See-
Also convention, to preserve correct semantics of cross ref-
erences.   This also requires attention when going the other
way, from news to mail.  See the discussion of  the  differ-
ence in section 6.5.