Private Mailbox
Most customers use a Private Mailbox due to its combination of privacy, repeatability, and API access. Private Mailboxes are the recommended Mailinator path for automated QA, CI/CD pipelines, AI-agent workflows, OTP testing, password resets, magic links, transactional email assertions, and SSO/OIDC identity flows. In addition, Private Mailboxes have several advantages over Public: 
Public Mailbox
The Public Mailinator system (i.e. every possible email address @mailinator.com) creates inboxes when emails arrives for them. All inboxes and emails are in the public domain. They are readable and delete-able by anyone. By design, there is NO privacy in the public Mailinator system. 
Message Delivery
Mailinator message flow diagram