In message <20130706021038(_dot_)30851(_dot_)qmail(_at_)joyce(_dot_)lan>, "John
Levine" writes:
IMO, the report is wrong on an essential detail. It attributes the
handling barrier to SMTP, which has no such barrier.
Surprisingly, the report is sort of right. The ABNF in RFC 2821
prohibits dotless domains, although the ABNF in 821 and 5321 allows
them. This was arguably a mistake in 2821 (it doesn't match the text)
but it says what it says.
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'.
No argument there. And a wide range of mail sending software treats a
dotless domain as a special case, appending search paths and otherwise
modifying it, so sending mail to an address at a dotless domain is an
exercise in flakiness.
There are 19 ccTLDs that have MX records at the top level. I wonder
if anyone has checked how well mail to them works. I am particularly
intruigued that Guatemala's and Trinidad's is outsourced to Google.
answer: ai 14391 MX 10 mail.offshore.ai
answer: ax 86392 MX 5 mail.aland.net
answer: cd 86400 MX 5 mail.nic.cd
answer: cf 10800 MX 0 mail.intnet.cf
answer: dm 86400 MX 10 mail.nic.dm
answer: gp 86400 MX 10 ns1.worldsatelliteservices.com
answer: gp 86400 MX 5 ns1.nic.gp
answer: gt 86400 MX 20 alt1.aspmx.l.google.com
answer: gt 86400 MX 20 alt2.aspmx.l.google.com
answer: gt 86400 MX 30 aspmx2.googlemail.com
answer: gt 86400 MX 30 aspmx3.googlemail.com
answer: gt 86400 MX 30 aspmx4.googlemail.com
answer: gt 86400 MX 30 aspmx5.googlemail.com
answer: gt 86400 MX 10 aspmx.l.google.com
answer: hr 14400 MX 5 alpha.carnet.hr
answer: io 604800 MX 10 mailer2.io
answer: kh 10800 MX 10 ns1.dns.net.kh
answer: km 3600 MX 100 mail1.comorestelecom.km
answer: lk 86400 MX 10 malithi-slt.nic.lk
answer: lk 86400 MX 20 malithi-lc.nic.lk
answer: mh 86400 MX 10 imap.pwke.twtelecom.net
answer: mq 86400 MX 10 mx1-mq.mediaserv.net
answer: pa 21600 MX 5 ns.pa
answer: tt 86400 MX 1 aspmx.l.google.com
answer: tt 86400 MX 10 alt1.aspmx.l.google.com
answer: ua 72072 MX 10 mr.kolo.net
answer: va 3600 MX 100 raphaelmx3.posta.va
answer: va 3600 MX 10 raphaelmx1.posta.va
answer: va 3600 MX 10 raphaelmx2.posta.va
answer: ws 21600 MX 10 mail.worldsite.ws
Which just shows 19 tld administrators that don't have clue. One
can add MX records at any node in the DNS inluding at the root.
That doesn't mean that it is sensible to add them or that they will
work reliably.
e.g.
. MX 0 some.domain.example.com.
_http._tcp.example.org. MX 0 some.domain.example.com.
As for SMTP supporting dotless domains of course it does, it was
designed when there was a single flat namespace. We got rid of
that flat namespace for good reasons which have not gone away.
Mark
R's,
John
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Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka(_at_)isc(_dot_)org
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