
Exploring Trust Relationships Through Global Scale SPF Mining - aspenmayer
https://medium.com/swlh/all-your-spf-are-belong-to-us-exploring-trust-relationships-through-global-scale-spf-mining-a666c7a7d368
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aspenmayer
> One other interesting aspect with SPF is it (potentially) reveals
> relationships with multiple email security providers. See the “Fortune 100
> Email Security Providers Listing (via SPF)” and “Domains with 4 or more
> Email Security Providers (via SPF)” gists below. In the Fortune 100 list,
> there are 3 domains with SPF relationships with more than one provider. If
> you look across all the top domains data you can see there are many. For
> anyone who has worked in the cyber security department at a large company
> before, this is not surprising, but it was cool to be able to see this in
> the data.

> Future Work SPF Crawler enhancements: As you can see from the SPF guide I
> shared above for “a” and “mx”, SPF supports some fairly complex policies for
> allowing certain IPs to send email (esp. the prefix operators on these SPF
> mechanisms). I did not provide support for these mechanisms in the first
> version of my SPF crawler mainly due to the complexity involved. Because of
> this, my results will under represent the trust relationships where these
> are used. I hope to add support for these operators to expand what could be
> found in this data.

For those who have trouble with the link:

[http://archive.today/5EJhG](http://archive.today/5EJhG)

