Companies Using Proton Mail

I looked at Proton Mail the way a mail administrator would, through DNS. Every domain on this page publishes an MX record, the entry that tells other mail servers where to deliver its email, and on 46,917 domains in our September 2026 crawl that record names Proton's servers first. 23,288 of them match a company record, and every size, industry and country figure below describes that matched half. Our DNS statistics for 2026 cover the records themselves.

Two records, two different stories

Proton asks for two things when you add a domain: a TXT record that proves you control it (protonmail-verification=) and the MX records that send mail its way. The TXT record is a receipt. It stays in DNS long after anyone stops using Proton, because nothing breaks when it goes stale. The MX record is live plumbing. If it points at Proton, Proton is receiving that domain's mail today.

Accept either record and you match 58,297 live domains. Looking up every MX record on 29 September 2026, we found 10,585 (18.2%) with the receipt and nothing else. Their mail goes to Google (3,099), Microsoft (1,899), Cloudflare's forwarding (350) and a long list of others, and 1,402 have no mail server at all. Another 793 keep Proton only as a backup. That is why this page reads 46,917 while the category table, which counts both records, reads 57,246.

Sales signal: a domain with the verification record and no Proton MX is a lead. Someone there tried Proton and kept their mail where it was.

The count over time

The usage chart has a single point for September 2026, because that's when we split the two records domain by domain. About one in eight of today's domains were first seen in August or September. That isn't a surge in sign-ups: the set of domains we crawl turns over each month, with dead sites dropping out and new ones found, and our coverage widens. 1,229 domains have dropped every Proton record since we began tracking in March 2026. It undercounts departures: a domain that moves its mail but keeps the TXT record still matches the looser test.

"Proton's verification record tells you someone once opened an account. Almost one domain in five that carries it sends its mail somewhere else." - David Thomson, CTO at TechnologyChecker.io

Sales signal: quote the September figure, and spend your attention on the switching data below. That is where real moves show up.

Who the customers are

Only 49.6% of Proton domains match a company. Many of the rest are personal domains, a freelancer's name or a family address. Among the matched companies, 89.2% have 1 to 10 staff and 9.01% have 11 to 50. The founding years are young: 43.64% in the 2010s and 38.07% in the 2020s. On Fastmail, another paid mail-only host, 23.24% of matched companies date from the 2020s.

Headcount shrinks sharply once you apply the MX test. Count every domain with a Proton record and 133 matched companies have more than 1,000 staff; count only those whose mail lands at Proton and it's 41. Large organisations often verify Proton and keep their corporate mail elsewhere. Solico Group, an Iranian food manufacturer, and San Antonio Shoemakers in Texas are among the larger names whose mail does land at Proton.

Sales signal: these are owner-operators who pay for privacy. Proton keeps custom domains for paid plans, so nearly every domain here is a setup someone chose and pays for.

Industries and countries

IT Services and IT Consulting leads at 8.92%, then Software Development (7.78%) and Technology, Information and Internet (6.52%). With Information Technology & Services, about a quarter of matched companies build or run technology. The tail holds rights groups and research networks such as Avocats Sans Frontières and the Global Initiative against Transnational Organized Crime.

The country table is where Proton parts from Fastmail. The United States leads with 7,259 matched companies, but the eleven European countries in the top 15 add up to 7,829. The Netherlands (1,720) is level with the United Kingdom (1,742), and 1,687 of the domains end in .nl. Switzerland, Proton's home, has 778 matched companies against 77 on our Fastmail profile.

Sales signal: treat this as a European list with a large US segment, not the other way round. Dutch and Swiss firms deserve their own campaigns, in their own languages.

Where Proton's new domains come from

Since March 2026, 709 domains moved their MX from Google Workspace to Proton Mail, 284 of them in the last 30 days and 566 in the last 90. We re-checked all 709 in September: every one routes mail to Proton, with no Google server left in the record. Only 92 domains went from Proton to Google Workspace.

Small flows need a base rate. 1,208 domains ran both Google Workspace and Proton at some point. At Google's usual drop rate across our crawl, about 19 of them would have left Google. 709 did, roughly 37 times the expected number. Microsoft 365 shows a weaker pull, 315 in and 104 out, but 41% of the domains that ever showed both still show both. That reads as a mixed setup rather than a switch, so we don't list it.

"The Google Workspace flow runs one way. For every domain that moved its mail from Proton to Google, more than seven moved from Google to Proton." - David Thomson, CTO at TechnologyChecker.io

Sales signal: the recent movers are the warmest leads on this page. A company that recently took its mail off Google Workspace may have given up Drive and Docs with it, and may be shopping for replacements that fit the same privacy stance.

The stack around the mailbox

The websites on these domains look more like small businesses than developer projects. Cloudflare sits in front of 44.01%, WordPress runs on 24.46% and GoDaddy hosts 12.27%, nearly twice its 6.54% on Fastmail domains, with Squarespace (6.29%) and Wix (4.19%) behind. Developer hosts are present but modest: Vercel 5.11%, GitHub Pages 3.02%, Netlify 2.54%. Google Analytics is on 28.2%, with Plausible (1.79%) and Matomo (1.49%) in the long tail.

Sales signal: the mail choice says privacy matters to this base, and the website choices say it wants tools that drop into WordPress or Squarespace. Privacy-first analytics and form builders are the obvious fit.

What reviewers say

G2 lists Proton Mail for Business at 4.6 out of 5 from 495 reviews, 78% of them five-star, as of 29 September 2026. Its AI summary rests on only a handful of mentions per theme, so this page carries no pros and cons block. Encryption and ease of use lead the praise; the complaints are search, storage and the limits of the free plan.

Sales signal: search and storage are the friction points. Tools that add archive search or extra storage around an encrypted mailbox have an obvious opening here.

Key takeaways

1. 46,917 domains route their mail to Proton first; 10,585 more only carry its verification record.

2. 89.2% of matched companies have 10 or fewer staff, and 38.07% were founded in the 2020s.

3. Eleven European countries hold 7,829 matched companies, against 7,259 in the US.

4. 709 domains moved from Google Workspace since March 2026, against 92 the other way.

5. Large companies mostly verify Proton and stop there: 133 on the raw count, 41 on the MX count.

How to use this list

Start with the 284 domains that left Google Workspace for Proton in the last 30 days, then filter on 1 to 50 staff in the Netherlands, Switzerland, the UK and the US. Treat any domain that shows Proton's verification record but routes its mail elsewhere as a separate, colder segment. For the full list of 46,917 Proton Mail domains with company, size and stack data, explore TechnologyChecker.io.