> ## Documentation Index
> Fetch the complete documentation index at: https://docs.paubox.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Paubox C# SDK

> Send HIPAA-compliant email and submit Paubox Forms from .NET applications using the official Paubox C# SDK.

The Paubox C# SDK is the official .NET client library for the [Paubox Email API](/email-api) and [Paubox Forms](/forms). It provides a strongly-typed interface for sending encrypted email, managing dynamic templates, tracking delivery, and submitting forms.

## Installation

The SDK is distributed as a compiled DLL. Download or clone the repository, then add a reference to `lib/Paubox.Email.API.dll` in your project.

**Visual Studio:** Right-click your project → Add → Reference → Browse → select `Paubox.Email.API.dll`.

**`.csproj` file:**

```xml theme={null}
<ItemGroup>
  <Reference Include="Paubox.Email.API">
    <HintPath>path\to\Paubox.Email.API.dll</HintPath>
  </Reference>
</ItemGroup>
```

## What you can do

* Send encrypted, HIPAA-compliant email to one or more recipients
* Send batches of up to 50 messages in a single API call
* Create, update, and delete dynamic Handlebars templates
* Send templated messages with per-message variable substitution
* Track delivery status and engagement per recipient
* Retrieve Paubox Form schemas and submit form responses with file attachments

## Requirements

* .NET 8.0 or later (.NET 9.0 also supported)

## Dependency injection

The SDK ships with `IEmailLibrary` and `IFormsLibrary` interfaces, making it straightforward to register the clients in an ASP.NET Core DI container and mock them in tests.

## Get started

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/csharp-sdk/quickstart">
    Add the DLL, configure credentials, and send your first email in minutes.
  </Card>

  <Card title="Authentication" icon="key" href="/csharp-sdk/authentication">
    Configure via constructor params or appsettings.json.
  </Card>

  <Card title="Email client" icon="envelope" href="/csharp-sdk/email-client">
    Full reference for sending email, managing templates, and tracking delivery.
  </Card>

  <Card title="Forms client" icon="file-lines" href="/csharp-sdk/forms-client">
    Retrieve form schemas and submit responses.
  </Card>
</CardGroup>