On Wed, 21 Oct 1998, Paul Mansfield wrote:
> I think its illegal. I believe that an MX record is of the form:
> <domain> IN MX <preference> <domain>
Forget about MX records. Have a read of RFC 821:
<domain> ::= <element> | <element> "." <domain>
<element> ::= <name> | "#" <number> | "[" <dotnum> "]"
<mailbox> ::= <local-part> "@" <domain>
<local-part> ::= <dot-string> | <quoted-string>
<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
This means that, for any message that is transmitted by SMTP, you are
not permitted to have an underscore in the domain part of the address.
Thus, domain names containing underscores, even if legal in the DNS,
would be of very limited legal use. You could generate a message to
user@underscored_domain (provided you didn't use SMTP to do so) and have
it delivered locally, or have the domain rewritten before delivering it
over SMTP (having looked it up in the DNS). But that's all.
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
--
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