How to send mail In EF core Razor pages

Question

I tried to send email when I create a IT tracker Request here In input fields I am Choosing The Mails in which I want To send The Mails.so My Entity class is

   public class Ittracker   
    {  
        //[Required]  
        [Required]  
        [RegularExpression("([a-zA-Z][a-zA-Z ]+)", ErrorMessage = "Only alphabets are allowed")]  
        public string Name { get; set; }  
         
        public int Id { get; set; }  
  
        [Required]  
        [RegularExpression("(^EST\d+$)", ErrorMessage = "Invalid EmployeCode  ")]  
          
        public string EmployeCode { get; set; }  
  
        [Required]  
        [EmailAddress]  
        public string EmailId { get; set; }  
        [Required]  
        public string Priority { get; set; }  
  
        [Required]  
        public string SupportType { get; set; }  
  
        [Required]  
        public string RequestDescription { get; set; }  
        public string Requeststatus { get; set; }  
  
        public string caseDetails { get; set; }  
  
        public string OptionalText { get; set; }  
  
  
        [DataType(DataType.Date)]  
        [BindProperty]  
        public DateTime? StartDate { get; set; }  
  
        [DataType(DataType.Date)]  
  
  
        [BindProperty]  
        public DateTime? EndDate { get; set; }  
  
        [BindProperty]  
        public DateTime? RequestDate { get; set; }  
  
  
        [BindProperty,EmailAddress, Required] //egulo pore add korei.migration e nei.  
        public string MainEmailRecever { get; set; }  
  
        [BindProperty, EmailAddress,Required]  
        public string CCEmailRecever { get; set; }  
  
  
    }

my CreateModel is

 public class CreateModel : PageModel  
    {  
        private readonly ApplicationDbContext _db;  
  
        [BindProperty]  
         
        public DateTime? RequestDate { get; set; }  
  
        [BindProperty]  
        public Ittracker Ittracker { get; set; }  
  
        [BindProperty]  
        public List PriorityList { get; set; }  
  
        [BindProperty]  
        public List SupportTypeList { get; set; }  
  
        [BindProperty]  
        public List RequeststatusList { get; set; }  
  
        //[BindProperty, EmailAddress, Required]  
        //public string MainEmailRecever { get; set; }  
  
        //[BindProperty, EmailAddress,Required]  
        //public string CCEmailRecever { get; set; }  
  
  
        //[BindProperty]  
        //public string EmployeCode { get; set; }  
        public CreateModel(ApplicationDbContext db)  
        {  
            _db = db;  
        }  
  
        public IActionResult OnGet(/*int? id*/)  
        {  
            //if (id == null)  
            //{  
            //    return NotFound();  
            //}  
            List p = new List { "Critical Priority", "High Priority", "Medium Priority", "Low Priority" };  
            PriorityList = p.Select(x => new SelectListItem { Text = x, Value = x }).ToList();  
  
            List s = new List { "Account Locked", "access Permission", "Email", "Desk Phone","Workstation","Application","VPN Access","FTP Account","Manex","Voyager" ,"Printing","Other"};  
            SupportTypeList = s.Select(x => new SelectListItem { Text = x, Value = x }).ToList();  
  
  
            List l = new List { "Active", "In Progress", /*"Resolved",*/ "Closed"/*, "Waiting" */};  
            RequeststatusList = l.Select(x => new SelectListItem { Text = x, Value = x }).ToList();  
            return Page();  
        }  
  
        public async Task OnPostAsync()  
        {  
            if (!ModelState.IsValid)  
            {  
                return Page();  
            }  
            var body = $@"Thank you, we have received your Request for User Code {Ittracker.EmployeCode} unit(s) of {Ittracker.Name}!  
                We will contact you if we have questions about your Request.  Thanks!
";  
            using (var smtp = new SmtpClient())  
            {  
                smtp.DeliveryMethod = SmtpDeliveryMethod.SpecifiedPickupDirectory;  
                smtp.PickupDirectoryLocation = @"D:\mailpickup";  
                var message = new MailMessage();  
                message.To.Add(Ittracker.MainEmailRecever);  
                message.CC.Add(Ittracker.CCEmailRecever);  
                message.Subject = "Ticket - New Issue";  
                message.Body = body;  
                message.IsBodyHtml = true;  
                message.From = new MailAddress("Arnab@eslatetech.com");  
                await smtp.SendMailAsync(message);  
  
                  
            }  
  
         _db.Ittracker.Add(Ittracker);  
         await _db.SaveChangesAsync();  
  
         return RedirectToPage("Index");  
             
            
  
  
            
        }

and My create.cshtml is

@page  
@model New11.Pages.Ittrackers.CreateModel  
@{  
    ViewData["Title"] = "Create";  
    Layout = "~/Pages/Shared/_Layout.cshtml";  
}  

  
Raise Request   

  
  
  
      
          
              
                RequesterName*  
              
              
                  
              
              
          
  
  
          
              
                RequesterEmpCode*  
              
              
                  
              
              
          
  
          
        @**@  
          
        @**@  
      
  
  
          
              
                RequesterEmailId*  
              
              
                  
              
              
          
  
          
              
                RequestDate  
              
              
                  
              
              
          
  
        @*  
              
                Priority  
              
              
                  
              
              
        *@  
          
              
                  
  
                    Priority*  
                  
                  
                      
                      
  
                        Critical Priority – Immediate - 30 minutes: Production down  
                        
  
                        High Priority– Immediate - 2 business hours: Loss of a major job duty  
                        
  
                        Medium Priority- Within 4 business hours: No production impact  
                        
  
                        Low Priority- Within 8 business hours: General request  
                      
                  
                  
              
          
  
        @*  
              
                  
              
              
                  
              
              
        *@  
  
          
              
                  
  
                    SupportType*  
                  
                  
                      
                  
                  
              
          
          
              
                Request Description*  
              
              
                  
                @**@  
                  
                    Please add as much detail as possible such as your computer name (look for a white label) and location (box build, RMA, shipping, ect...). The more the better! You can also include screenshots by using the file attachment option.  
                  
              
              
          
  
  
  
  
  
        @*  
              
                  
              
              
                  
              
              
        *@  
  
  
          
              
                  
  
                    Request Status *  
                  
                  
                      
                  
                  
              
          
        @*  
              
                StartDate  
              
              
                  
              
              
              
  
          
              
                EndDate  
              
              
                  
              
              
        *@  
  
          
              
                  
              
              
                  
                @**@  
              
              
          
  
  
          
              
                Text(Optional)  
              
              
                  
                @**@  
              
              
          
  
          
              
                  
              
              
  
                  
              
              
          
  
          
              
                  
              
              
  
                  
              
              
          
          
              
                  
              
          
      
  
  
@section Scripts{  
    @{ await Html.RenderPartialAsync("_ValidationScriptsPartial"); }  
}

so now while I am executing this in my PickupDirectoryLocation the mails are being Created but it not Sending The mails

when I was Debugging In smtp it is throwing A exception named " ServicePoint = 'smtp.ServicePoint' threw an exception of type 'System.InvalidOperationException'".

Can anyone suggest what I am doing wrong?