User-Registration Email Validator

I need an automated system that verifies the legitimacy of every email address entered during user registration. The critical requirement is a robust mail server check—real-time pinging of MX records and SMTP handshakes to confirm that the inbox actually exists before we let the user proceed. Classic syntax or domain-only checks are not enough for our use-case, though you are free to layer them in if it helps achieve near-zero false positives.

Please outline in a detailed project proposal how you will:

• Architect the validation flow so it can be called via REST or direct library import • Handle high-volume concurrency without slowing the sign-up form • Return a clear pass / fail / uncertain status we can log and act upon • Package the code (preferred languages are Python, Node, or Go, but I’m open to your recommendation) along with unit tests and setup instructions

I will review proposals that specify the tools, libraries, and success metrics you plan to use, plus an estimated timeline for each milestone. Budget: USD 10–30 Skills: PHP, Python, Linux, Software Architecture, Node.js, Backend Development, RESTful API, API Development