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Re: Underscore in Host names



> 
>    ----- Transcript of session follows -----
> ... while talking to yukon.cren.org.:
> >>> MAIL From:<descombes@ima_vms.enst.fr>
> <<< 501-                    ^
> <<< 501 Path data: Extra garbage before terminating ">"
> 554 <listproc@yukon.cren.org>... Remote protocol error
> 
>    ----- Message header follows -----
> 
> Underscore is legal, Zmailer 2.9.3-940816 is rejecting them ????
> 
Not quite.
Although it is acceptable for RFC-822 but it is NOT acceptable
for Internet host according to RFC-952 and RFC-1123.
Host/domain names can consist of: letters, digits and hyphen.
Thats all.
Here is a fragment of the grammar [RFC-952]:
	     <name>  ::= <let>[*[<let-or-digit-or-hyphen>]<let-or-digit>]
RFC-1123 states it this way:
   2.1  Host Names and Numbers

	 The syntax of a legal Internet host name was specified in RFC-952
	 [DNS:4].  One aspect of host name syntax is hereby changed: the
	 restriction on the first character is relaxed to allow either a
	 letter or a digit.  Host software MUST support this more liberal
	 syntax.

Jurek

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Jerzy Sobczyk              ____________ ___     Institute of Control and
J.Sobczyk@ia.pw.edu.pl    /  /     |  |/  _\    Computation Engineering, 
tel.+48 2 6210070        /  /  /|  |  |  (____         Warsaw University 
              ext.7297  /  /  _>|  |  |\____  \            of Technology
fax.+48 22 253719      /__/__/__|__|__|_____)  \       Nowowiejska 15/19
tlx. 813 307 pw pl    /________________________/   00-665 Warsaw, POLAND 
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