ietf-smtp
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Re: domain name definition in RFC2821

2006-04-22 00:00:51
On Fri, 21 Apr 2006 21:44:03 PDT, Yuri Inglikov said:
There appears to be some disconnect between ABNF syntax and a prose. I.e. i t
appears that ABNF requires at least 2 sub-domain parts, while prose discu sses
"one or more dot-separated components". Which one is "more correct" an d any
scenario when a single-component domain name can be valid / useful in modern
SMTP?

Can you give an example of a "single-component domain name" that would *not*
be flagged as a failure to canonalize to a FQDN?

Are there any e-mail addresses that *work* (or even could *potentially* work)
of the form 'userid(_at_)com' or 'userid(_at_)net' or 
'some(_dot_)full(_dot_)name(_at_)to' or anything
else like that?

(And even if you require 2 components, it's traditionally been ugly.  There
were a *lot* of university computing centers and comp-sci departments that were
quite surprised when all the addresses of the form 
'userid(_at_)server(_dot_)cs' or
'userid(_at_)server(_dot_)cc' were no longer recognized as a shorthand for
'server.cs.foo.edu' or 'server.cc.bar.edu'.  And some of us were around for
when British schools leaked reverse-order domain names, and 
'user(_at_)uk(_dot_)ac(_dot_)FOO(_dot_)cs'
went to another country rather than to U of Foo's CS dept...)

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