It can be annoying to receive a 500 error while using Nodemailer in a Vercel production build to deliver SMTP messages. With an emphasis on SMTP settings and environment variable configuration, this tutorial tackles typical problems and their fixes. It's important to make sure your environment variables are set appropriately on Vercel. In addition, the document offers code examples for both frontend and backend implementations of Nodemailer and describes how to use it with any SMTP server.