I’m looking for a Kotlin developer to add a one-time-password feature that is delivered by Email, not SMS or in-app. The code must generate a secure numeric or alphanumeric OTP, send it via email, and automatically reject it once its time-based expiration window closes. You may choose the email transport you prefer—Gmail API, Outlook, or a custom SMTP server—so long as setup steps are clearly documented. Clean, idiomatic Kotlin is essential, and I’d like the module to drop straight into my existing Android codebase without heavy refactoring. Deliverables • Kotlin source that creates, emails, and verifies the OTP with an adjustable expiry time • Simple configuration file or constants for SMTP/API credentials, sender address, timeout length, and code length • A concise README explaining integration steps and any third-party libraries used • Demo unit test (or small sample activity) that shows the full flow from request to validation I’ll handle UI styling; you focus on bullet-proof logic, proper error handling, and clear documentation. If you’ve implemented similar email-based OTP systems before, I’d love to see a short code snippet or repo link when you bid.