public class DiskSmtpClient : SmtpClient
    {
        public DiskSmtpClient(IOptionsSnapshot<MailKitOptions> mailOptionsSnapshot)
        {
            if (mailOptionsSnapshot.Value.SpecifiedPickupDirectory)
            {
                SpecifiedPickupDirectory = true;
                PickupDirectoryLocation = mailOptionsSnapshot.Value.PickupDirectoryLocation;
            }
            
        }
        public bool SpecifiedPickupDirectory { get; set; }
        public string PickupDirectoryLocation { get; set; }

        public override Task SendAsync(MimeMessage message, CancellationToken cancellationToken = new CancellationToken(),
            ITransferProgress progress = null)
        {
            if (!SpecifiedPickupDirectory)
                return base.SendAsync(message, cancellationToken, progress);
            return SaveToPickupDirectory(message, PickupDirectoryLocation);

        }

    



        private async Task SaveToPickupDirectory(MimeMessage message, string pickupDirectory)
        {
            using (var stream = new FileStream($@"{pickupDirectory}\email-{Guid.NewGuid().ToString("N")}.eml", FileMode.CreateNew))
            {
                await message.WriteToAsync(stream);
            }
        }

       

        public override Task ConnectAsync(string host, int port = 0, SecureSocketOptions options = SecureSocketOptions.Auto,
            CancellationToken cancellationToken = new CancellationToken())
        {
            if (!SpecifiedPickupDirectory)
                return base.ConnectAsync(host, port, options, cancellationToken);
            return Task.CompletedTask;
        }



        public override Task DisconnectAsync(bool quit, CancellationToken cancellationToken = new CancellationToken())
        {
            if (!SpecifiedPickupDirectory)
                return base.DisconnectAsync(quit, cancellationToken);

            return Task.CompletedTask;
        }
    }

 services.AddTransient<DiskSmtpClient>();

  var email = "mail@dotnettips.info";
            var subject = "subject";
            var message = "message";

            var emailMessage = new MimeMessage();

            emailMessage.From.Add(new MailboxAddress("DNT", "do-not-reply@dotnettips.info"));
            emailMessage.To.Add(new MailboxAddress("", email));
            emailMessage.Subject = subject;
            emailMessage.Body = new TextPart(TextFormat.Html)
            {
                Text = message
            };

            
                _client.SpecifiedPickupDirectory = true;
                _client.PickupDirectoryLocation = "c:\\mail";

                _client.LocalDomain = "dotnettips.info";
                await _client.ConnectAsync("smtp.relay.uri", 25, SecureSocketOptions.None).ConfigureAwait(false);
                await _client.SendAsync(emailMessage).ConfigureAwait(false);
                await _client.DisconnectAsync(true).ConfigureAwait(false);

services.Configure<MailKitOptions>(options => Configuration.GetSection("MailKitOptions").Bind(options));

  "MailKitOptions": {
    "SpecifiedPickupDirectory": true,
    "PickupDirectoryLocation": "c:\\mail"
  }

    public class MailKitOptions
    {
        public  bool SpecifiedPickupDirectory { get; set; }
        public  string PickupDirectoryLocation { get; set; }
    }

public class SampleDbContext : IdentityDbContext
{
    public SampleDbContext() : base("DefaultConnection") { }

    static SampleDbContext()
    {
        Database.SetInitializer(new DropCreateDatabaseIfModelChanges<SampleDbContext>());
    }

    public DbSet<UserProfile> UserProfiles { get; set; }
    public DbSet<Customer> Customers { get; set; }
    public DbSet<Product> Products { get; set; }
    ...
}

public void ForEach(Action<T> action)
{
  if (action == null)
    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.match);
  for (int index = 0; index < this._size; ++index)
    action(this._items[index]);
}

public static void ForEach<T>(T[] array, Action<T> action)
{
  if (array == null)
    throw new ArgumentNullException("array");
  if (action == null)
    throw new ArgumentNullException("action");
  for (int index = 0; index < array.Length; ++index)
    action(array[index]);
}

() => { int a = 1; }

 public string GetHour(DateTime lastdate)
        {
            PersianCalendar pc = new PersianCalendar();
            string result = " ساعت " + (((pc.GetHour(lastdate)) < 10) ? ("0" + pc.GetHour(lastdate).ToString()) : (pc.GetHour(lastdate)).ToString()) + ":" + (((pc.GetMinute(lastdate)) < 10) ? ("0" + pc.GetMinute(lastdate).ToString()) : (pc.GetMinute(lastdate)).ToString());
            return result;
        }

public string getDay(DayOfWeek day)
        {
            string Result = "";
            switch (day)
            {
                case DayOfWeek.Friday:
                    Result = "جمعه";
                    break;
                case DayOfWeek.Monday:
                    Result = "دوشنبه";
                    break;
                case DayOfWeek.Saturday:
                    Result = "شنبه";
                    break;
                case DayOfWeek.Sunday:
                    Result = "یکشنبه";
                    break;
                case DayOfWeek.Thursday:
                    Result = "پنج شنبه";
                    break;
                case DayOfWeek.Tuesday:
                    Result = "سه شنبه";

                    break;
                case DayOfWeek.Wednesday:
                    Result = "چهارشنبه";
                    break;
                default:
                    break;
            }
            return Result;
        }

getDay(pc.GetDayOfWeek(LastDate))

public string GetMounth(int month)
        {
            string[] monthInYear = {"فروردین","اردیبهشت","خرداد","تیر","مرداد","شهریور","مهر","آبان","آذر","دی","بهمن","اسفند" };
            return monthInYear[month-1];
        }

private void btnGetDate_Click(object sender, EventArgs e)
        {
            DateTime LastDate = DateTime.Parse(txtLastDate.Text);
            TimeSpan ts = DateTime.Now - LastDate;
            PersianCalendar pc = new PersianCalendar();
            int DifferenceYear = DateTime.Now.Year - LastDate.Year;
            int DiffernceMounth = DateTime.Now.Month - LastDate.Month;
            if(DateTime.Now.Month>LastDate.Month)
                DiffernceMounth = DateTime.Now.Month - LastDate.Month; 
            else
            DiffernceMounth=LastDate.Month-DateTime.Now.Month;
            int DifferenceDays = ts.Days;

            StringBuilder Result = new System.Text.StringBuilder("");
           
            if(DifferenceYear>0)
            {
                Result.Append(DifferenceYear.ToString() + " سال پیش"+" ، "+getDay(pc.GetDayOfWeek(LastDate))+" "+pc.GetDayOfMonth(LastDate).ToString()+" " + GetMounth(pc.GetMonth(LastDate))+" " +pc.GetYear(LastDate)+GetHour(LastDate));
            }
            else if(DiffernceMounth>0)
            {
                Result.Append(DiffernceMounth.ToString() + " ماه پیش" + " ، " + getDay(pc.GetDayOfWeek(LastDate)) + " " + pc.GetDayOfMonth(LastDate).ToString() + " " + GetMounth(pc.GetMonth(LastDate)) + " " + pc.GetYear(LastDate) + GetHour(LastDate));
            }
            else if(DifferenceDays>0)
                Result.Append(DifferenceDays.ToString() + " روز پیش" + " ، " + getDay(pc.GetDayOfWeek(LastDate)) + " " + pc.GetDayOfMonth(LastDate).ToString() + " " + GetMounth(pc.GetMonth(LastDate)) + " " + pc.GetYear(LastDate) + GetHour(LastDate));
            else if(DifferenceDays==0)
                Result.Append(" امروز" + " ، " + getDay(pc.GetDayOfWeek(LastDate)) + " " + pc.GetDayOfMonth(LastDate).ToString() + " " + GetMounth(pc.GetMonth(LastDate)) + " " + pc.GetYear(LastDate) + GetHour(LastDate));

            lblResult.Text = Result.ToString();
        }

An unhandled exception of type 'System.Reflection.TargetInvocationException' occurred in mscorlib.dll

Additional information: Exception has been thrown by the target of an invocation.

private void button1_Click(object sender, EventArgs e)
        {
            if (_worker != null && _worker.IsBusy)
            {
                return;
            }

            _worker = new BackgroundWorker
            {
                WorkerReportsProgress = true,
                WorkerSupportsCancellation = true
            };
            _worker.DoWork += workerDoWork;
            _worker.ProgressChanged += workerProgressChanged;
            _worker.RunWorkerCompleted += workerRunWorkerCompleted;
            _worker.RunWorkerAsync();
        }

private void workerDoWork(object sender, DoWorkEventArgs e)
        {
            //var interval = (int)(1000 / _capture.Fps);
            Image image;
            while ((image = _capture.QueryFrame().ToBitmap()) != null &&
                    _worker != null && !_worker.CancellationPending)
            {
                _worker.ReportProgress(0, image);
                //Thread.Sleep(interval);

                Thread.Sleep(10);
            }
        }
        private void workerProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            var image = e.UserState as Image;
            if (image == null) return;

            //Cv.Not(image, image);
            //_pictureBoxIpl1.RefreshIplImage(image);
            //_pictureBoxIpl1.Image=image;

            _pictureBoxIpl1.Invoke(new EventHandler(delegate
            {
                _pictureBoxIpl1.Image = image;
            }));

            
        }

        private void workerRunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            _worker.Dispose();
            _worker = null;
        }