I think you forgot something!
Note the connection to port 25. I did not say to send anything on that port
to verify the domain, just open the port. To verify that the port is not
valid for the www.example.com domain, you would need to send an email to
that domain! Talk about spam!
Guy
spammers will start to forge www.example.com
receivers will observe that www.example.com has no mx record
receivers will try to connect to port 25
receivers will observe that www.example.com is not an mta
this knowledge can be recorded in some sort of rfc-ignorant type
system or reputation ssytem or whatever.
-----Original Message-----
From: owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com
[mailto:owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com] On Behalf Of David
Woodhouse
Sent: Wednesday, September 15, 2004 11:48 AM
To: spf-discuss(_at_)v2(_dot_)listbox(_dot_)com
Subject: RE: [spf-discuss] Wildcard DNS entry
On Wed, 2004-09-15 at 11:31 -0400, guy wrote:
If example.com and www.example.com share the same system, port 25 will
work. So, the receivers will accept the mail.
Not necessarily. It depends how the system is set up. If he doesn't want
'www.example.com' to be a valid mail domain, but he configures the
machine with that A (or AAAA) record to actually accept mail for it,
then that's really _his_ fault for misconfiguring his mail server.
For example, the machine which has the web server (and hence the A and
AAAA records) for the 'www.woodhou.se' domain _does_ also run a mail
server, because it handles mail for a number of domains -- but that
domain isn't one of them:
$ telnet www.woodhou.se 25
Trying 2002:d592:9a28::1...
Connected to www.woodhou.se (2002:d592:9a28::1).
Escape character is '^]'.
220-pentafluge.infradead.org ESMTP Exim 4.42 Wed, 15 Sep 2004 16:38:44 +0100
220 Be gentle with me
helo me
250 pentafluge.infradead.org Hello me [2002:c35c:fd02::1]
mail from:<postmaster(_at_)infradead(_dot_)org>
250 OK
rcpt to:<david(_at_)woodhou(_dot_)se>
250 Accepted
rcpt to:<david(_at_)www(_dot_)woodhou(_dot_)se>
550 Relay not permitted
quit
--
dwmw2
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