According to Live Direct Marketing's daily Tranco top-1M scan (September 17, 2026), the top 1 million websites route email through 231 identifiable mailbox providers. The largest is Self-Hosted at 22.50% of domains with MX records. This page ranks them all and links to a full guide for each.
Key facts
231 mailbox providers tracked across 673,136 domains with MX records (Tranco top-1M, 2026-09-17).
Largest: Self-Hosted — 22.50% of domains with MX records.
Combined share of all tracked mailbox providers: 100.0%.
Every row links to a data-backed guide; figures update daily.
A domain's mailbox provider is decided by its MX records — the DNS entries that tell the world where to deliver its mail. Reading MX across the Tranco top-1M gives a clean, unbiased map of who actually runs the world's inboxes, because it measures configuration, not marketing claims.
Three forces dominate the picture. First, the hyperscale suites — Google Workspace and Microsoft 365 — which between them anchor a large share of business email and keep growing as small companies abandon self-managed servers. Second, self-hosting, still surprisingly large but in slow structural decline. Third, a long and instructive tail of hosting companies, registrars and regional providers that matters enormously for anyone sending mail into a specific country or vertical.
Mailbox-provider share across the Tranco top-1M, by domains publishing MX records (updated daily).
Full ranking — all 231 mailbox providers
Share = % of domains with MX records in the Tranco top-1M. Click any name for its full guide.
Every mailbox provider filters mail by its own rules. Gmail weights engagement and domain reputation heavily; Microsoft 365 leans on its own SmartScreen signals and is notoriously sensitive to sudden volume; regional hosts often run stricter, less forgiving greylisting. If a meaningful share of your audience sits behind a provider you never test against, your inbox-placement rate is a guess. The ranking below is the starting point for deciding which seed mailboxes actually represent your recipients.
Are your emails landing in spam? Run a free inbox-placement test across Gmail, Outlook, Yahoo and more — see exactly where your mail lands and why.
Self-Hosted is the most common mailbox provider in the Tranco top-1M, used by 151,440 domains (22.50% of domains with MX records) as of September 17, 2026.
How many mailbox providers are there in the top 1M?
Live Direct Marketing's scan identifies 231 distinct mailbox providers with at least a handful of domains each, as of 2026-09-17.
