I need a straightforward desktop application that runs smoothly on Windows and lets me send high-volume email campaigns through Gmail and my own custom SMTP server. The only must-have feature right now is reliable bulk sending; open-rate tracking or list management can wait for a later phase. Here is what I expect: • A clean UI where I can paste or import a list of recipient addresses, compose the subject/body (HTML or plain text), and hit send. • The app should connect to any SMTP host I enter (server, port, SSL/TLS, username, password) and respect common sending limits I set—threads, delays, or batch size—to avoid server throttling. • Basic delivery feedback is useful (success/fail log, error messages), but I do not need advanced analytics. • Please package everything as a Windows installer or portable executable and include source code plus a short setup guide so I can tweak it later. The language or framework is up to you—Python, C#, Java, Electron, or anything you are comfortable with—as long as it produces a stable Windows build. When you reply, let me know your preferred tech stack, an estimated timeline, and if you have past experience building SMTP bulk senders.