.NET

dotnet add package SendFlit

using SendFlit;

using var sf = new Client(Environment.GetEnvironmentVariable("SENDFLIT_API_KEY")!);

var res = await sf.SendAsync(new Email
{
    From = "you@yourdomain.com",
    To = "user@example.com",
    Subject = "Confirm your email",
    Html = "<p>Click <a href='https://app.example.com/confirm?t=abc'>here</a>.</p>",
    Text = "Confirm your email: https://app.example.com/confirm?t=abc",
});

Console.WriteLine($"{res.Id} {res.Status}");

var email = new Email
{
    From = "billing@yourdomain.com",
    To = "user@example.com",
    Subject = "Your receipt",
    Html = "<p>Your receipt is attached.</p>",
};

email.Attach("receipt.pdf", await File.ReadAllBytesAsync("receipt.pdf"), "application/pdf");
email.Attach("notes.txt", "Thanks for your order.", "text/plain");

await sf.SendAsync(email);

var results = await sf.BatchAsync(new List<Email>
{
    new() { From = "news@yourdomain.com", To = "a@example.com", Subject = "Digest", Html = "<p>Hi A</p>" },
    new() { From = "news@yourdomain.com", To = "b@example.com", Subject = "Digest", Html = "<p>Hi B</p>" },
});

var page = await sf.ListEmailsAsync(limit: 20, offset: 0);   // returns a JsonElement

var domain = await sf.AddDomainAsync("yourdomain.com");   // returns a JsonElement
Console.WriteLine(domain.GetProperty("id").GetString());

var all = await sf.ListDomainsAsync();

// Run after the DNS records are live. Changes can take time to propagate.
var state = await sf.VerifyDomainAsync(domain.GetProperty("id").GetString()!);

await sf.SuppressAsync("user@example.com", "unsubscribe");

var usage = await sf.UsageAsync();   // usage counts for your account, as a JsonElement

using SendFlit;

// Read the raw body before anything parses it.
using var buffer = new MemoryStream();
await Request.Body.CopyToAsync(buffer);
var raw = buffer.ToArray();

var ok = Client.VerifyWebhookSignature(
    Environment.GetEnvironmentVariable("SENDFLIT_WEBHOOK_SECRET")!,
    raw,
    Request.Headers["X-Sendflit-Signature"].ToString());

if (!ok)
{
    return Results.StatusCode(401);
}
// parse raw and handle the event here

try
{
    await sf.SendAsync(email);
}
catch (SendFlitException e) when (e.Status == 422)
{
    Console.Error.WriteLine($"Invalid email: {e.Body}");
}