usefor-article-04 April 2001

5.2.  From

   The From header contains the electronic address(es), and possibly the
   full name, of the article's author(s). The content syntax makes use
   of syntax defined in [MESSFOR], subject to the following revised
   definition of local-part.

      From-content        = mailbox-list
      addr-spec           = local-part "@" domain
      local-part          = dot-atom / strict-quoted-string

        NOTE: This syntax ensures that the local-part of an addr-spec is
        restricted to pure US-ASCII (and is thus in strict compliance
        with [MESSFOR]), whilst allowing any UTF-8 character to be used
        in a preceding quoted-string containing the author's full name.
        If some future extension to the Mail protocols should relax this
        restriction, one would expect the Netnews protocols to follow.

   The mailbox in the From-content SHOULD be a valid address, belonging
   to the poster(s) of the article, or person or agent on whose behalf
   the post is being sent (see the Sender header, 6.2).  When, for
   whatever reason, the poster does not wish to include such an
   adddress, the From-content SHOULD then be an address which ends in
   the top level domain of ".invalid" [RFC 2606].

        NOTE: Since such addresses ending in ".invalid" are
        undeliverable, user agents Ought to warn any user attempting to
        reply to them and Ought Not, in any case, to attempt to deliver
        to them (since that would be pointless anyway).  Whether or not
        a valid address can subsequently be extracted from such an
        address falls outside the scope of this standard (though it
        would be pointless to use a disguise so easily penetrable).

        Be warned also that some injecting agents that have
        authentication information may choose to replace the From-
        content based upon the authenticated identity.

--- ../usefor-article-03/From.out          February 2000
+++ ../usefor-article-04/From.out          April 2001
@@ -16,8 +16,22 @@
         If some future extension to the Mail protocols should relax this
         restriction, one would expect the Netnews protocols to follow.
 
-   Any mailbox in the From-content MUST belong to one of the poster(s)
-   of the article, or be a mailbox which he is authorized by its owner
-   to use, or be an address which ends in the top level domain of
-   ".invalid" [RFC 2606].
+   The mailbox in the From-content SHOULD be a valid address, belonging
+   to the poster(s) of the article, or person or agent on whose behalf
+   the post is being sent (see the Sender header, 6.2).  When, for
+   whatever reason, the poster does not wish to include such an
+   adddress, the From-content SHOULD then be an address which ends in
+   the top level domain of ".invalid" [RFC 2606].
+
+        NOTE: Since such addresses ending in ".invalid" are
+        undeliverable, user agents Ought to warn any user attempting to
+        reply to them and Ought Not, in any case, to attempt to deliver
+        to them (since that would be pointless anyway).  Whether or not
+        a valid address can subsequently be extracted from such an
+        address falls outside the scope of this standard (though it
+        would be pointless to use a disguise so easily penetrable).
+
+        Be warned also that some injecting agents that have
+        authentication information may choose to replace the From-
+        content based upon the authenticated identity.