Send Email Using ASP.NET Core 5 Web API

Introduction

Sending emails using ASP.NET Core 5 Web API can be accomplished using the built-in SmtpClient class or external libraries like SendGrid. Below, I’ll provide an example using SmtpClient to send emails via SMTP:

1. Create a New ASP.NET Core Web API Project:
   Use the following command to create a new ASP.NET Core Web API project:

   dotnet new webapi -n EmailSenderDemo
   cd EmailSenderDemo

2. Configure SMTP Settings:
   In your appsettings.json file, add the SMTP settings:

   {
     "SmtpSettings": {
       "Host": "your-smtp-host",
       "Port": 587,
       "Username": "your-username",
       "Password": "your-password",
       "SenderEmail": "sender@example.com",
       "SenderName": "Your Sender Name"
     },
     // Other settings
   }

Replace the placeholders with your actual SMTP server details.

3. Install NuGet Packages:
   Install the necessary NuGet package for sending emails via SMTP:

   dotnet add package System.Net.Mail

4. Create an Email Service:
   Create an email service class that encapsulates the email sending logic. You can create a new class called EmailService.cs:

   using Microsoft.Extensions.Configuration;
   using System.Net;
   using System.Net.Mail;
   using System.Threading.Tasks;

   public class EmailService : IEmailService
   {
       private readonly SmtpSettings _smtpSettings;

       public EmailService(IConfiguration configuration)
       {
           _smtpSettings = configuration.GetSection("SmtpSettings").Get<SmtpSettings>();
       }

       public async Task SendEmailAsync(string toEmail, string subject, string body)
       {
           using (var client = new SmtpClient(_smtpSettings.Host, _smtpSettings.Port))
           {
               client.UseDefaultCredentials = false;
               client.Credentials = new NetworkCredential(_smtpSettings.Username, _smtpSettings.Password);
               client.EnableSsl = true;

               var message = new MailMessage
               {
                   From = new MailAddress(_smtpSettings.SenderEmail, _smtpSettings.SenderName),
                   Subject = subject,
                   Body = body,
                   IsBodyHtml = true
               };
               message.To.Add(new MailAddress(toEmail));

               await client.SendMailAsync(message);
           }
       }
   }

5. Create a DTO for SMTP Settings:
   Create a DTO (Data Transfer Object) class to hold SMTP settings:

   public class SmtpSettings
   {
       public string Host { get; set; }
       public int Port { get; set; }
       public string Username { get; set; }
       public string Password { get; set; }
       public string SenderEmail { get; set; }
       public string SenderName { get; set; }
   }

6. Inject the Email Service:
   Register the email service in the Startup.cs file:

   services.AddSingleton<IEmailService, EmailService>();

7. Create a Controller:
   Create a controller to send emails. You can create a new controller called EmailController.cs:

   using Microsoft.AspNetCore.Mvc;
   using System.Threading.Tasks;

   [ApiController]
   [Route("api/[controller]")]
   public class EmailController : ControllerBase
   {
       private readonly IEmailService _emailService;

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

       [HttpPost]
       public async Task<IActionResult> SendEmail([FromBody] EmailRequest request)
       {
           await _emailService.SendEmailAsync(request.ToEmail, request.Subject, request.Body);
           return Ok("Email sent successfully");
       }
   }

8. Run the Application:
   Start the application using the following command:

   dotnet run

You can use tools like curl, Postman, or a browser to send POST requests to the /api/email endpoint with the appropriate JSON payload, such as:

   {
       "toEmail": "recipient@example.com",
       "subject": "Test Email",
       "body": "<h1>Hello, this is a test email.</h1>"
   }

This example demonstrates how to send emails using the SmtpClient class in an ASP.NET Core 5 Web API. Remember that for production use, it’s important to handle exceptions and errors, and consider using more advanced email libraries or services like SendGrid for enhanced features and deliverability.