How to send email in asp.net core

First create your interface

    public interface IEmailSender
    {
        Task SendEmailAsync(string email, string subject, string message);
      
    }

Implement the interface

public class EmailSender : IEmailSender
{
        private readonly EmailConfiguration _emailConfig;


        public EmailSender(IOptions<EmailConfiguration> emailConfig)
        {
            _emailConfig = emailConfig.Value;
        }


        public async Task SendEmailAsync(string email, string subject, string htmlMessage)
        {
            var message = new MimeMessage();
            message.From.Add(new MailboxAddress(_emailConfig.DisplayName, _emailConfig.From));
            message.To.Add(MailboxAddress.Parse(email));
            message.Subject = subject;


            message.Body = new TextPart(TextFormat.Html)
            {
                Text = htmlMessage
            };


            using var client = new SmtpClient();


            try
            {
                await client.ConnectAsync(
                    _emailConfig.SmtpServer,
                    _emailConfig.Port,
                    true
                    //MailKit.Security.SecureSocketOptions.StartTlsWhenAvailable
                    );


                //client.AuthenticationMechanisms.Remove("XOAUTH2");


                await client.AuthenticateAsync(
                    _emailConfig.UserName,
                    _emailConfig.Password);


                await client.SendAsync(message);
            }
            finally
            {
                await client.DisconnectAsync(true);
                client.Dispose();
            }
        }




    }

Create a class named EmailConfiguration

    public class EmailConfiguration
    {
        public string From { get; set; }
        public string DisplayName { get; set; }
        public string SmtpServer { get; set; }
        public int Port { get; set; }
        public string UserName { get; set; }
        public string Password { get; set; }
        public string DefaultSubjectPrefix { get; set; } = "Message";
    }

In your appsettings.json

  "EmailConfiguration": {
    "From": "your email here",
    "SmtpServer": "smtp.gmail.com",
    "DisplayName": "Your app name",
    "Port": 465,
    "UserName": "the same email here",
    "Password": "input your password",
    "DefaultSubjectPrefix": "Message"
  }

Packages

MailKit.Net.Smtp
MimeKit

Register the service in your Program.cs

builder.Services.AddScoped<IEmailSender, EmailSender>();