SOLORIFF/email-authentication-by-industry

Email authentication by industry and company size

Who actually authenticates their email: SPF and DMARC adoption measured over public DNS across 13,635 company domains in 25 industries, broken down by employee count.

Published by SoloRiff. Source page, with the interactive table and the full method: https://soloriff.com/data/email-authentication

Measured 2026-09-03. Refreshed monthly.

The headline

Adoption tracks company size far more strongly than it tracks industry.

Company size	Publish SPF	Publish DMARC	Enforce DMARC
1–10	88.2%	61.7%	21.4%
11–50	92.1%	74.6%	32.1%
51–200	93.8%	86.2%	47.3%
201–1,000	96.9%	89.6%	61.1%
1,000+	97.9%	95.5%	79.5%

58 points between the smallest companies and the largest. Weighted by sample size across all 25 industries.

"Enforce" means a DMARC policy of quarantine or reject. A policy of p=none is counted as publishing DMARC but not as enforcing it: it reports failures and stops nothing. Across the whole sample, 81.7% publish DMARC and 48.4% enforce it — a third of all companies have a DMARC record that does nothing.

Files

File	What it is
email-authentication-census.csv	122 rows — one per industry × size band
email-authentication-census.json	The same rows plus the method and a column dictionary

Columns

Column	Meaning
industry	Industry slug
industry_label	Industry, human readable
size_band	1-10, 11-50, 51-200, 201-1000, 1001-plus
sample_size	Company domains measured in this cell
measured_at	Date of the DNS measurement (ISO 8601)
spf_pct	% publishing any SPF record
spf_all_open_pct	% whose SPF record ends in +all, which authorises any sender
dmarc_pct	% publishing any DMARC record, including p=none
dmarc_enforced_pct	% with a DMARC policy of quarantine or reject
no_dmarc_pct	% publishing no DMARC record at all
mx_pct	% with an MX record (100 by construction — see method)

Method

One domain per company, deduplicated. Domains are sampled within employee-count bands for each industry, then queried over public DNS:

• TXT at the apex for SPF
• TXT at _dmarc.<domain> for DMARC
• MX to establish that the domain receives mail at all

Every individual row is reproducible with dig.

Domains with no MX record are excluded. A domain that cannot receive mail is usually parked, a redirect or a defensive brand registration rather than a company that sends and receives email; counting those as authentication failures would drag every percentage down and make the result an artefact of the sample.

Cells with fewer than 60 domains are not published, and appear as blank rather than as a number nobody should trust.

DKIM is not measured. A DKIM key lives at <selector>._domainkey.<domain>, and selectors cannot be enumerated from outside the domain — only guessed. A company with flawless DKIM under a selector we did not guess would be recorded as having none, so the figure would describe our guess list rather than the industry. Only records published at fixed, discoverable names are measured here.

Licence

CC BY 4.0. Free to reuse, including commercially, with attribution to SoloRiff and a link to https://soloriff.com/data/email-authentication.

Only aggregate counts are published. The underlying company domains are never released.

Citation

SoloRiff (2026). Email authentication by industry and company size. https://soloriff.com/data/email-authentication