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Re: [Asrg] What are the IPs that sends mail for a domain?

2009-07-02 06:25:09


--On 1 July 2009 11:12:13 -0400 Dotzero <dotzero(_at_)gmail(_dot_)com> wrote:

On Wed, Jul 1, 2009 at 11:00 AM, John Leslie<john(_at_)jlc(_dot_)net> wrote:

  That's closer... But I'd argue that no SPF construct "authorizes"
sending email. In practice, I think it's quite clear that SPF constructs
merely express probabilities.


What is the probability that you will receive legitimate email
originating from ibm.com?

ibm.com text = "v=spf1 -all"

Nil. They don't use the domain for outbound email. They use country specific subdomains like @uk.ibm.com.

I'm not sure why they publish MX records for @ibm.com - perhaps they have some initial contact addresses @ibm.com, but don't reply using that domain.

It's very sensible of them to use the -all spf record, adding a little protection for their brand reputation.

Alternatively, this is a massive cock-up and a huge potential embarrassment. I don't think so, though. Our logs from June show no inbound email (either accepted or rejected) from the @ibm.com domain, but a few dozen emails from @uk.ibm.com and some from the 'be', 'ca', 'us', 'jp', 'hu' subdomains of ibm.com.

Exercise for the reader: why aren't spammers using the @ibm.com domain?
--
Ian Eiloart
IT Services, University of Sussex
01273-873148 x3148
For new support requests, see http://www.sussex.ac.uk/its/help/
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