On Mon, 22 Apr 1996 16:52:57 EDT
"Paul M. Karagianis" <[log in to unmask]>wrote:
>
>I have a subscriber who is getting errors on administrative Listserv
>mail from SMTP on our IBM _and_ from LSMTP on our Alpha.  The only
>book I have here (1) with a definition of what's valid in a FQDN says
>the underscore, as used below, is legal.
 
According to Internet RFC 1912 ("Common DNS Operational and Configuration
Errors", February 1996, D. Barr, The Pennsylvania State University):
 
   Allowable characters in a label for a host name are only ASCII letters,
   digits, and the "minus" character.  ....
   The presence of underscores in  a label is allowed in [RFC 1033],
   except [RFC1033] is informational only, and was not defining a standard. ...
   Note that the rules for Internet host names also apply to hosts and
   addresses used in SMTP (See RFC 821).
 
One notable "violation" I've recently seen is in the name of the WWW site
operated on behalf of the Deputy Prime Minster and Minister of Canadian
Heritage, the Honourable Sheila Copps, namely:
 
    http://HON_S_COPPS.PCH.GC.CA
 
which is the "Ope'ration Drapeau" site.