[Solved] ASP.Net Core Identity Error: Email is not real

I have the below code to send email after a user is registered but I am getting that it is not a real email!

public async Task<bool> SendEmailAsync(string email, string subject, string confirmLink)
{
    try
    {
        MailMessage message = new MailMessage();
        SmtpClient smtpClient = new SmtpClient();
        message.From = new MailAddress("ramiwahdan2023@gmail.com");
        message.To.Add(email);
        message.Subject = subject;
        message.IsBodyHtml = true;
        message.Body = confirmLink;

        smtpClient.Port = 465;
        smtpClient.Host = "smtp.ionos.com";


        smtpClient.EnableSsl = true;
        smtpClient.UseDefaultCredentials = false;
        smtpClient.Credentials = new NetworkCredential("info@dr-maha-habib.com", "Fatima@2020");
        smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
        smtpClient.Send(message);
        return true;
    }
    catch (Exception)
    {
        return false;
    }
}
public async Task<IActionResult> OnPostAsync(string returnUrl = null)
{
    returnUrl ??= Url.Content("~/");
    ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList();
    if (ModelState.IsValid)
    {
        var user = new AppUser
        {
            FirstName = Input.FirstName,
            LastName = Input.LastName,
            UserName = Input.Email,
            Email = Input.Email
        };

        await _userStore.SetUserNameAsync(user, Input.Email, CancellationToken.None);
        await _emailStore.SetEmailAsync(user, Input.Email, CancellationToken.None);
        var result = await _userManager.CreateAsync(user, Input.Password);

        if (result.Succeeded)
        {
            _logger.LogInformation("User created a new account with password.");

            var userId = await _userManager.GetUserIdAsync(user);
            var code = await _userManager.GenerateEmailConfirmationTokenAsync(user);
            code = WebEncoders.Base64UrlEncode(Encoding.UTF8.GetBytes(code));
            var callbackUrl = Url.Page(
                "/Account/ConfirmEmail",
                pageHandler: null,
                values: new { area = "Identity", userId = userId, code = code, returnUrl = returnUrl },
                protocol: Request.Scheme);

            await SendEmailAsync(Input.Email, "Confirm your email",
                $"Please confirm your account by <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>clicking here</a>.");

            if (_userManager.Options.SignIn.RequireConfirmedAccount)
            {
                return RedirectToPage("RegisterConfirmation", new { email = Input.Email, returnUrl = returnUrl });
            }
            else
            {
                await _signInManager.SignInAsync(user, isPersistent: false);
                return LocalRedirect(returnUrl);
            }
        }
        foreach (var error in result.Errors)
        {
            ModelState.AddModelError(string.Empty, error.Description);
        }
    }