Window Service

Installing

dotnet add package Microsoft.Extensions.Hosting.WindowsServices

Configuration

builder.Services.AddWindowsService(options =>
{
    options.ServiceName = "AutoSendEmail";
});
builder.Services.AddHostedService<Worker>();

Create Class Contact

public class Contact{
    public int ContactId { get; set; }
    public string Email { get; set; } = null!;
    public string Subject { get; set; } = null!;
    public string Body { get; set; } = null!;
}

Create Class BaseRepository

public abstract class BaseRepository{
    protected IConfiguration configuration;
    public BaseRepository(IConfiguration configuration) => this.configuration = configuration;
}

Create Class ContactRepository

public class ContactRepository : BaseRepository{
    public ContactRepository(IConfiguration configuration) : base(configuration){ }
    public IEnumerable GetContacts(){
        using(IDbConnection connection = new SqlConnection(configuration.GetConnectionString("Store"))){
            return connection.Query("SELECT * FROM Contact WHERE EndTime IS NULL AND StartTime <= GETDATE();");
        }
    }
    public int Update(IEnumerable list){
        using(IDbConnection connection = new SqlConnection(configuration.GetConnectionString("Store"))){
            string sql = "UPDATE Contact SET EndTime = GETDATE() WHERE ContactId IN @Ids";
            return connection.Execute(sql, new { Ids = list});
        }
    }
}

Class MailSettings

public class MailSettings{
    public string Host { get; set; } = null!;
    public short Port { get; set; }
    public string Email { get; set; } = null!;
    public string Password { get; set; } = null!;
}

Class EmailSender

public class EmailSender
{
    MailSettings settings;
    public EmailSender(IOptions options) => settings = options.Value;
    public async Task Send(Contact obj){
        try{
            using SmtpClient client = new SmtpClient{
                Host = settings.Host,
                EnableSsl = true,
                Port = settings.Port,
                Credentials = new NetworkCredential(settings.Email, settings.Password),
                UseDefaultCredentials = false
            };
            var message = new MailMessage{
                From = new MailAddress(settings.Email),
                Subject = obj.Subject,
                Body = obj.Body
            };
            message.To.Add(new MailAddress(obj.Email));
            await client.SendMailAsync(message);
            return 1;
        }catch{
            return 0;
        }        
    }
}

Class Worker

public class Worker : BackgroundService{
    EmailSender sender;
    ContactRepository repository;
    public Worker(EmailSender sender, IConfiguration configuration) {
        this.sender = sender;
        repository = new ContactRepository(configuration);
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            IEnumerable contacts = repository.GetContacts();
            if(contacts != null && contacts.Count() > 0){
                List list = new List();
                foreach (Contact item in contacts){                  
                    if(await sender.Send(item) > 0){
                            list.Add(item.ContactId);
                    }
                }
                repository.Update(list);
            }
            await Task.Delay(10000, stoppingToken);
        }
    }
}

Publish Service

dotnet publish --output "D:\Services"

Create Service

sc.exe create "AutoSendEmail" binpath="d:\Services\AutoSendEmail.exe"

Start Service

sc.exe start "AutoSendEmail"

Stop Service

sc.exe stop "AutoSendEmail"

Delete Service

sc.exe delete "AutoSendEmail"