Re: [EXIM] Underscore in hostname

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Auteur: Philip Hazel
Date:  
À: Rudolf Kompf
CC: exim-mailing-list
Sujet: Re: [EXIM] Underscore in hostname
On Tue, 15 Sep 1998, Rudolf Kompf wrote:

> I want to upgrade to version 2.03. Deliver to such address as
> kompf@m_post.ife-le.de does now fail (m_post IN CNAME omega)
> (see error-mail below); but doesn't in 1.90!


Underscores are not legal in domain names. The following change was made
to Exim at version 1.921:

  10. Domains in addresses that come in via SMTP commands (MAIL FROM, RCPT TO,
  VRFY) are now checked according to the more restrictive RFC 821 syntax rather
  than RFC 822 syntax. This syntax is that of a DNS domain.                


Here is the extract from RFC 821:

            <domain> ::=  <element> | <element> "." <domain>


            <element> ::= <name> | "#" <number> | "[" <dotnum> "]"


            <name> ::= <a> <ldh-str> <let-dig>                          


            <ldh-str> ::= <let-dig-hyp> | <let-dig-hyp> <ldh-str>


            <let-dig> ::= <a> | <d>                               


            <let-dig-hyp> ::= <a> | <d> | "-"            


            <a> ::= any one of the 52 alphabetic characters A through Z 
                    in upper case and a through z in lower case       


            <d> ::= any one of the ten digits 0 through 9      



Interestingly, you are the first to have trouble with this. Previous
complaints about underscore have all been to do with the arguments of
HELO commands.

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.



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