Providers
A handful of companies sit in front of most of the world's inboxes
Gmail, Outlook and Yahoo decide, in milliseconds, what you see first. Here is how much they handle.
Most people never run a mail server. They have an account with one of a few providers, and those providers scan, sort and deliver almost everything. That concentration is the reason blocklists and reputation scores matter so much.
What the big providers handle
- Gmail has more than a billion users. Google has said for years that Gmail blocks more than 100 million phishing messages a day.
- Microsoft Outlook, Hotmail and Microsoft 365 together cover a large share of business mailboxes.
- Yahoo and AOL still have a large base, especially in the United States and parts of Europe.
- Apple iCloud Mail, Proton and regional providers cover much of the rest.
What happens inside a provider
- Connection checks: the sending IP, reverse DNS and reputation are read before the message is accepted.
- Authentication: SPF, DKIM and DMARC results are checked against the domain in the From line.
- Content and behaviour: links, attachments and how users treat similar mail all feed the score.
- Feedback: the "report spam" button is a direct input to the next decision.
Why it matters to you
- A rule change at one provider can move your delivery overnight. Watch the postmaster tools those providers publish.
- Your reputation follows your sending domain, not your code.