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Re: [ietf-smtp] Dotless domains and email

2013-07-05 16:24:15
On 7/5/2013 1:56 PM, John Levine wrote:
All I'm saying is that there's a lot of existing and useful practice
which expects to be able to distinguish an alias (presumably without a
dot) from a FQDN. ...

Well, yes.  Take a look at SAC 053 and see if there's anything they
missed:

http://www.icann.org/en/groups/ssac/documents/sac-053-en.pdf


IMO, the report is wrong on an essential detail. It attributes the handling barrier to SMTP, which has no such barrier.

Here's my summary of the situation:

1. SMTP does not prohibit dotless domains. So, as far as the protocol is concerned foo@example is as legal as foo(_at_)example(_dot_)com.

2. A wide range of independently-developed mail-receiving software treats a dotless hostname as /not/ a legal domain name and thereby filters it out as potentially hostile. A common example that justifies this is 'localhost'.

So there is indeed a widespread, very solid email barrier to usage of dotless hostnames, although it is from long-standing receiving software practice, rather than from the protocol specification.



d/
--
Dave Crocker
Brandenburg InternetWorking
bbiw.net
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