What are test mailbox networks?

Test mailbox networks are large collections of email accounts distributed across multiple providers, maintained by testing services for placement measurement.

These networks typically include:

Accounts at all major consumer providers (Gmail, Outlook, Yahoo). Corporate and enterprise domain accounts. Regional and international provider coverage. Varied account ages and characteristics.

Automated systems check these mailboxes after test sends and report where messages landed. Scale enables statistical confidence in results.

A fleet of observer vessels stationed at every major port, reporting conditions back to headquarters.