# Correo

**Correo** is a .NET service designed for programmatically sending emails. It supports communication through two simultaneous channels:

- **HTTP (via REST API)**
- **Pub/Sub Messaging (via NATS)**

Correo can be integrated with various email mediators, offering flexible configuration options.

## Mediator Configuration

Correo supports multiple email mediators, configured using the following setting:

```json
"SmtpMediator": "SmtpClient" // Options: SmtpClient, SendGrid, Mailgun
```

## Supported Mediators

### SMTP Servers
Correo supports integration with standard SMTP email servers, including:

- **Local SMTP servers**
- **Gmail**
- **Yahoo**

SMTP integration is possible using either of two libraries: **.NET's built-in SMTP client** or **MailKit**. The configuration section in `appsettings.json` is as follows:

```json
"SmtpClient": {
  "Package": "MailKit", // Options: .NET, MailKit
  "Server": "smtp.gmail.com",
  "Port": "587",
  "UseAuthentication": true,
  "Authentication": {
    "UserName": "<account>@gmail.com",
    "Domain": "",
    "Password": "********"
  },
  "EnableSsl": true,
  "TrustServer": false
}
```

### Transactional Email APIs

Correo also supports transactional email APIs for scalable email sending solutions:

#### **SendGrid**
[SendGrid](https://app.sendgrid.com/) is a cloud-based SMTP provider that simplifies email sending without managing servers. It provides an easy-to-use API and a free plan allowing up to 100 emails per day.

To configure SendGrid, generate an API key from the SendGrid platform and update `appsettings.json`:

```json
"SmtpMediator": "SendGrid",
"SendGrid": {
  "ApiKey": "xxxxxxxxxxx"
}
```

#### **Mailgun**
[Mailgun](https://app.mailgun.com/) is an email automation service that offers transactional email APIs, with free and pay-as-you-go pricing options.

To configure Mailgun, generate an API key from Mailgun and specify the domain name in `appsettings.json`:

```json
"SmtpMediator": "Mailgun",
"Mailgun": {
  "ApiKey": "xxxxxxxxxxx",
  "Domain": "xxxxxxxxxxx"
}
```

## Logging

Correo uses **Serilog** for logging, which can be configured in `appsettings.json`. It supports logging to multiple destinations:

- **File-based logging**
- **PostgreSQL database logging**
- **Seq (structured log management)**

The logging configuration section:

```json
"Logs": {
  "File": {
    "Enabled": false,
    "Path": "logs/log.txt"
  },
  "Postgres": {
    "Enabled": false,
    "Connection": "Host=<host>;Port=5432;User ID=<user>;Password=<password>;Database=<database>;"
  },
  "Seq": {
    "Enabled": false,
    "Url": "",
    "ApiKey": ""
  }
}
```

## Hosting

Correo is primarily tested in **Docker** environments, but as it is built on **.NET 8**, it is cross-platform and can likely be hosted in various environments, including **Linux, Windows, and Kubernetes clusters**.

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For further details and updates, visit the project repository or documentation.