Proxy tester through SMTP

Project to be made in Visual Studio. Project Goal: To find proxies that work with given smtp servers and are sending mail successfully. Project is 2 simple tasks. Task 1) Take a list of proxies and test all of them by sending 1 email through a given list of smtp accounts.(SSL) Task 2) Download the sent emails via pop3 and gather the proxies that were able to send successfully. Software must be able to utilize multiple threads to be able to check thousands of proxies in a short period of time.