EmailService

DeltaCore.EmailService

DeltaCore.EmailService is a .NET 8-based library that provides email services with support for sending verification emails (OTP), caching mechanisms (using Memory or Redis), and retry policies for robust email delivery.

Features

• Send Email: Easily send emails with customizable subjects and body content.
• Send OTP: Securely send one-time password (OTP) emails for user verification.
• OTP Verification: Verify OTP codes to ensure secure user validation.
• Caching Support: Store OTPs in-memory or Redis to improve performance.
• Retry Mechanism: Automatically retries sending emails in case of failure using exponential backoff.
• Customizable Email Templates: Customize OTP email templates with placeholders.

Installation

You can install the DeltaCore.EmailService NuGet package in your .NET 8 project by running the following command in your terminal:

dotnet add package DeltaCore.EmailService

Alternatively, you can search for DeltaCore.EmailService on NuGet and install it directly.

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Usage

• Setting Up Email Service To use the SMTPService class, you need to configure your email settings in the appsettings.json file:

{
  "SMTPSettings": {
    "SMTPHost": "smtp.your-email-provider.com",
    "SMTPPort": 587,
    "SMTPUser": "your-email@example.com",
    "SMTPPassword": "your-email-password",
    "FromEmail": "your-email@example.com",
    "OrganizationName": "Your Organization",
    "OTPHtmlBodyTemplate": "<h3>Your verification code is: {code}</h3>"
  }
}

In your Program.cs (for .NET 8, this file replaces Startup.cs), register the SMTPService as a singleton service:

using DeltaCore.EmailService;

var builder = WebApplication.CreateBuilder(args);

// Register services to the container
builder.Services.AddSingleton<IEmailService, SMTPService>();
builder.Services.Configure<SMTPSettings>(builder.Configuration.GetSection("SMTPSettings"));

// Add other services
builder.Services.AddMemoryCache(); // Required for MemoryCache
builder.Services.AddStackExchangeRedisCache(options =>
{
    options.Configuration = builder.Configuration.GetConnectionString("RedisConnection");
});

// Build and run the application
var app = builder.Build();
app.MapGet("/", () => "Hello World!");
app.Run();

• Sending an Email You can send an email like this:

  public class EmailController : ControllerBase
{
    private readonly IEmailService _emailService;

    public EmailController(IEmailService emailService)
    {
        _emailService = emailService;
    }

    public async Task<IActionResult> SendVerificationEmail(string email)
    {
        var result = await _emailService.SendEmailAsync(email, "Welcome", "Welcome to our service!", CancellationToken.None);
        return Ok(result ? "Email sent successfully" : "Failed to send email");
    }
}

• Sending OTP You can send an OTP (One-Time Password) for email verification:

public async Task<IActionResult> SendOTP(string email)
{
    var result = await _emailService.SendOTPAsync(email, IEmailService.cashIn.REDIS, CancellationToken.None);
    return Ok(result ? "OTP sent successfully" : "Failed to send OTP");
}

• Verifying OTP To verify the OTP:

public async Task<IActionResult> VerifyOTP(string email, string code)
{
    var result = await _emailService.VerifyOTP(email, code, IEmailService.cashIn.REDIS);
    return Ok(result ? "OTP verified successfully" : "Invalid OTP");
}

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Configuration Options

• SMTPHost: SMTP server host (e.g., smtp.gmail.com).

• SMTPPort: Port for the SMTP server (usually 587 or 465).

• SMTPUser: Your email username for authentication.

• SMTPPassword: Your email password or app-specific password.

• FromEmail: The email address from which emails will be sent.

• OrganizationName: The name of your organization (used in the email template).

• OTPHtmlBodyTemplate: The HTML template for the OTP email.

• Use {code} and {organization} placeholders.

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Caching Options

The library supports two caching mechanisms for OTP storage:

• Memory: Stores OTP in-memory (using MemoryCache).

• Redis: Stores OTP in a Redis database (requires RedisCacheService).

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Retry Mechanism

The SMTPService uses a retry policy with exponential backoff. It will retry sending emails up to three times if it encounters an error, waiting 2, 4, and 8 seconds between attempts.

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Logging

DeltaCore.EmailService integrates with ILogger for logging. You can log messages related to email sending, OTP generation, and verification.

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Contributing

Feel free to fork the repository, make improvements, and submit pull requests. Please ensure that your contributions follow the existing coding standards and include appropriate tests.

• Fork the repository.

• Clone your fork and create a new branch.

• Make your changes and commit them.

• Push to your fork and submit a pull request.

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License

This project is licensed under the MIT License.

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Support

If you encounter any issues or have questions about using DeltaCore.EmailService, feel free to create an issue on GitHub or reach out to us.

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Example Usage Flow:

• Send OTP: When a user registers, send them an OTP to verify their email address.

• Verify OTP: User submits the OTP they received, and you verify it.

• Send Email: Once the OTP is verified, send a welcome email or any other relevant communication.

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Author

👤 Ahmed Nady