Does anyone know why RFC 2821 added the dotless domain restriction?
Like 5321, 821 permits dotless domains by its construction rules:
This same discussion came up on this list in January 2009. Here's a
snippet from a discussion between John Klensin and John Levine:
Date: Sat, 24 Jan 2009 20:27:15 -0500
From: John C Klensin <john+smtp(_at_)jck(_dot_)com>
To: John Levine <johnl(_at_)taugh(_dot_)com>, ietf-smtp(_at_)imc(_dot_)org
> As best I understand it, the prose description of addresses in
> 2821 allowed TLDs in addresses, but the ABNF didn't. In 5321
> the ABNF changed to match the prose. Although the DNS allows
> you to put a dot at the end of a domain name to make it clear
> that it's an absolute address, SMTP has never allowed that.
Correct on all counts. In the 2821bis work, the possibility of
changing the syntax to match the prose was considered too. That
change was actually made to the document at one point. The
group then decided it was a bad idea and the change was un-done.
The archaeologists might want to dig into the rest of it. My personal
archives don't go back that far.
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