UseSend 1.4.0

useSend .NET SDK

.NET client for the useSend email API. useSend is an open-source alternative to Resend, SendGrid, Mailgun and Postmark.

Installation

dotnet add package UseSend

Quick Start

With Dependency Injection (ASP.NET Core)

// Program.cs
builder.Services.AddUseSend("us_your_api_token");

// In your service/controller — inject IUseSend or a specific service interface
public class WelcomeSender(IUseSend useSend)
{
    public async Task SendWelcomeAsync(string to)
    {
        var response = await useSend.Emails.SendAsync(new EmailMessage
        {
            From    = "noreply@yourdomain.com",
            To      = to,
            Subject = "Welcome!",
            Html    = "<h1>Welcome aboard!</h1>",
        });

        if (response.Success)
            Console.WriteLine($"Email sent: {response.Content}");
    }
}

// Or inject only the service interface you need
public class DomainChecker(IEmailService emails, IDomainService domains) { ... }

Self-Hosted useSend

builder.Services.AddUseSend(options =>
{
    options.ApiToken = "us_your_api_token";
    options.ApiUrl   = "https://send.mycompany.com/api/"; // your self-hosted instance
});

Without Dependency Injection

var client = UseSendClient.Create("us_your_api_token");

var response = await client.Emails.SendAsync(new EmailMessage
{
    From    = "noreply@yourdomain.com",
    To      = "user@example.com",
    Subject = "Hello",
    Text    = "Hello from useSend!",
});

Environment Variable

If you prefer not to hardcode your token, set the USESEND_API_KEY environment variable and create the client with no arguments:

var client = UseSendClient.Create(); // reads USESEND_API_KEY

Features

Examples

• ConsoleNoDi — Standalone usage without dependency injection
• WebMinimalApi — ASP.NET Core minimal API with DI
• ConsoleSelfHosted — Custom host URL for self-hosted useSend
• WebIdentity — ASP.NET Core Identity with email confirmation and password reset

Authentication

All API calls require a Bearer token. Create one in your useSend Developer Settings.

Error Handling

By default, failed API calls throw a UseSendException. To receive errors as return values instead:

builder.Services.AddUseSend(options =>
{
    options.ApiToken        = "us_your_api_token";
    options.ThrowExceptions = false;
});

var response = await useSend.Emails.SendAsync(email);

if (!response.Success)
    Console.WriteLine($"Error {response.Exception!.StatusCode}: {response.Exception.ApiError}");

API Reference

Full API documentation: docs.usesend.com/api-reference