In your previous mail you wrote:

   From: Eijiro Sumii <eijiro_sumii@anet.ne.jp>
   > I reported the same problem with MS IE on Japanese Windows to
   > webmaster@brion.inria.fr on March 18
   
   In fact,
   
     http://caml.inria.fr/contact.en.html
   
   shows the address
   
     mailto:webmaster@caml.inria.fr
   
   but I doubt that it is legial according to RFC, since caml.inria.fr is
   CNAME in the DNS.

=> aliases (CNAME left parts) are legal in mail addresses.

   Indeed, my server at Penn rewrites it to
   brion.inria.fr in order to conform to the standard.
   
=> it rewrites it because it checkes it and gets the canonical name as
a side effect, not because aliases are not legal...

Francis.Dupont@enst-bretagne.fr

PS: alias is a DNS concept, SMTP requires valid names (aliases or canonical
names) with a restriction in the character set (only digits, letters and
the character "-" not in the first position) for labels (names are made up
by labels separated by dots). Note that SMTP does not require the name
exists...