← All insights · Thu, 02 Jul 2026

83.4% of the web's email runs on just 3 providers

A handful of gatekeepers receive most of the world's mail. What it means for senders.

Across 50,000 domains, mail hosting is strikingly concentrated:

Top 1 provider handles 32.4% of mail-enabled domains
Top 3 handle 83.4%
Top 5 handle 92.1%, out of 20 distinct providers we detected

Leaders right now: Other / self-hosted (32.4%), Google Workspace / Gmail (28.3%), Microsoft 365 / Outlook (22.7%), Proofpoint (5.6%), Mimecast (3.1%).

For senders this cuts two ways. Most of your deliverability outcome is decided by a few gatekeepers, get right with them and you reach the majority of inboxes. But the long tail is where surprises live: a small self-hosted or regional gateway can silently greylist or block you with rules nothing else uses. You can't assume "it worked for Gmail" means "it works everywhere", which is why verifying against the actual receiving server matters.

Free deliverability tools → Check any domain (MX, SPF, DMARC), test your own inbox placement scored out of 100, generate SPF and DMARC records, or run a blocklist check, all free with no signup and nothing stored, at deliverability.mailtester.ninja/tools.

Verify a real address → This is aggregate DNS data. To check whether a specific email address exists and is deliverable, use MailTester Ninja , real-time, nothing stored.

Data: MailTester Ninja Email Infrastructure Index, 50,000 domains, snapshot Mon, 20 Jul 2026 04:18:17 GMT. Reuse freely under CC BY 4.0.

FAQ

How concentrated is the email hosting market?

In this sample the top 3 providers handle 83.4% and the top 5 handle 92.1% of mail-enabled domains.

Data · Email checker · Email verifier · Blocklist checker · Blocklists explained · Widget

Built & updated automatically by MailTester Ninja, the email verifier that stores nothing. DNS-only, aggregate data, no personal information. · JSON API · RSS