Are you building a .NET library that needs to send SMTP emails? One of the key considerations in such a library is to provide fault tolerance when sending emails. After all, there could be a number of reasons why the email may not be delivered – the SMTP server could be down, the credentials could be incorrect, or the message could be invalid. To ensure that your library handles these scenarios gracefully, you can use Polly for .NET. In this tutorial, we’ll show you how to use Polly to provide fault tolerance in your .NET library for sending SMTP emails. We’ll start by creating a new .NET library project, then show you how to add the required packages and set up the project. We’ll also walk you through how to implement the SmtpEmailService class, which sends the actual email, and how to register it with Polly in the ServiceRegistration class. By the end of this tutorial, you’ll have a .NET library that is fault-tolerant when sending SMTP emails, thanks to the power of Polly.