MailOnce

MailOnce is a fast, privacy-focused temporary email service designed for receiving verification emails, OTP codes, sign-up confirmations, verification links, and other short-lived messages without exposing or cluttering your primary inbox. Users can create a temporary email address instantly and receive incoming messages in real time through a clean browser-based inbox. MailOnce automatically detects OTP codes and verification links inside emails, making common verification flows faster and easier to complete. MailOnce supports multiple temporary email domains, custom email addresses, quick address changes, manual inbox refresh, and device linking so an inbox can be accessed across devices when needed. Temporary inboxes are browser-scoped and automatically expire, keeping the experience simple without requiring users to create a traditional account for basic temporary email use. The service is useful for everyday users who need a disposable address for registrations and online verification, but MailOnce is also built with developers and QA testers in mind. It can be used to test authentication flows, OTP delivery, passwordless login emails, account verification, confirmation links, onboarding emails, and other email-based product workflows without filling a personal or work inbox with test messages. Key features include real-time email delivery, automatic OTP detection, verification-link detection, multiple temporary email domains, custom addresses, fast inbox switching, device linking, and a responsive inbox that works across desktop and mobile browsers. For developers, MailOnce also maintains an open-source Developer Kit on GitHub with examples and workflows for testing OTP emails, verification links, and email-based QA scenarios. Additional developer-focused capabilities are being explored for the future, including APIs, webhooks, SDKs, and more advanced automated email-testing workflows. MailOnce focuses on keeping temporary email fast and straightforward: generate an address, receive the message, find the code or verification link, and continue with what you were doing. No unnecessary setup is required for the core experience. Whether you're protecting your primary inbox during a one-time sign-up, receiving an OTP, testing a new authentication system, or validating an application's email delivery flow, MailOnce provides a simple temporary inbox built around verification and testing.