Global SPF Deployment

500 sites tested
0 DNS errors
260 with SPF


500 sites tested
0 DNS errors
247 with SPF


500 sites tested
0 DNS errors
221 with SPF


500 sites tested
0 DNS errors
206 with SPF


500 sites tested
0 DNS errors
220 with SPF


3083 sites tested
235 DNS errors
1054 with SPF

South Korea

500 sites tested
0 DNS errors
293 with SPF

United Kingdom

500 sites tested
0 DNS errors
229 with SPF

United States

500 sites tested
0 DNS errors
209 with SPF

What do these numbers mean?

This experiment attempts to answer the following question: If an average user had a working installation of SPF on their machine, how useful would it be to them? What percentage of the services and sites the average user regularly accesses are SPF-enabled? In other words, the experiment attempts to quantify the usefulness of SPF to the average end user, given the current deployment of SPF in the Internet.

The experiment does not track how many users or hosts use SPF in the current Internet. It also does not track how many sites have configurations of SPF that are not accessible by average users from the Internet.

The Sender Policy Framework (SPF) is an extension to the Simple Mail Transfer Protocol (SMTP). SPF allows software to identify and reject forged addresses in the SMTP MAIL FROM (Return-Path), a typical nuisance in e-mail spam.

The IETF statistics are based on a list of domain names that are derived from the email addresses of currently-active document authors of Internet Engineering Task Force (IETF) documents. This data set was included to investigate if the organizations that IETF authors come from are more progressive in deploying SPF, compared to the rest of the Internet.

How are these numbers generated?

The scripts that update this page retrieve the names of the web sites that are most popular across the globe, as well as in select countries, from in regular intervals. They then check whether the DNS entry for each site name reflects that it uses SPF. The numbers above show the percentage of these top sites that are SPF-enabled, as well as the absolute numbers.

Note that although the DNS entry for a site may indicate that SPF is available, this does not necessarily mean that actually using SPF with the site will succeed. I’ll eventually add code to verify that SPF can be used with sites that claim to enable it.

How representative are these numbers?

They’re reasonably representative, but not perfect. One issue is that the sample sets are very small; typically offers lists of 100 to 500 top sites for free, depending on the country. More importantly, though, the sample sets are derived from web site names, because that’s all offers. It is not clear that checking SPF deployment based on a set of web site names is resulting in numbers that represent deployment of SPF in the broader Internet.

Attention, operators: I’m interested in basing these statistics on a more meaningful data set. If you can provide me with a regularly-updated list of most-frequently-looked-up DNS names – or, for SPF or DKIM, a list of the domains that generate the most inbound email – please contact me at please enable javascript to view . The larger your network and the longer the list, the better.

How have these numbers been changing over time?

Funny you should ask. The graphs below (click on each image to get a PDF that lets you zoom in) illustrate the weekly changes of SPF deployment in the various sample sets since these measurements started in October 2007:

SPF deployment trends - click to zoom in (PDF)

This graph shows the same data as the one above, but zooms in on the interesting area:

SPF deployment trends (magnified) - click to zoom in (PDF)

Significant jumps in the historic data (e.g., fall 2008 or spring 2009) are usually due to changing what data they make available, or on tracking bugs having been fixed. The latter fixes are often based on suggestions of visitors to this page. See the acknowledgements below.

Download deployment trends as text: global cn de fi in jp kr uk us ietf

Acknowledgements and Changes