我正在尝试使用 smtp 从 angular 2.0 的 asp.net core web api 向多个用户发送电子邮件但它抛出的 CORS 错误

如何解决我正在尝试使用 smtp 从 angular 2.0 的 asp.net core web api 向多个用户发送电子邮件但它抛出的 CORS 错误

下面是我的错误：

Access to XMLHttpRequest at 'https://localhost:44359/api/ClientCandidateBulkStatusUpdate' from origin 'http://localhost:4200' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

我在 startup.cs 中进行了如下设置：

public void ConfigureServices(IServiceCollection services)
    {
        services.AddCors(options =>
        {
            options.AddPolicy("CorsPolicy",builder => builder.AllowAnyOrigin()
                .AllowAnyMethod()
                .AllowAnyHeader()
                // .SetIsOriginAllowed(origin => true)//allow any origin
                .AllowCredentials());
               // .Build());
                
        });
                    
        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1); 
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app,IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseHsts();
        }
        var builder = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddJsonFile("appsettings.json",optional: true,reloadOnChange: true)
        .AddJsonFile($"appsettings.{env.EnvironmentName}.json",optional: true);

        builder.AddEnvironmentvariables();
        builder.Build();
        app.UseCors("CorsPolicy");
        ////app.UseCors(builder1 => builder1
        ////    .AllowAnyOrigin()
        ////    .AllowAnyMethod()
        ////    .AllowAnyHeader()
        ////    .SetIsOriginAllowed(origin => true)//allow any origin
        ////    .AllowCredentials());// allow credentials
        
        app.UseHttpsRedirection();
        app.UseMvc();
    }

我像在控制器上启用了 CORS

 [Route("api/[controller]")]
[ApiController]
[EnableCors("CorsPolicy")]
public class ClientCandidateBulkStatusUpdateController : ControllerBase
{}

我的发送邮件代码是：

public void Sendmail(String MailFrom,String Mailto,String Subject,String Body,String CC = "",Boolean copy = false)
    {
        DataTable EmailSettingsDT = new DataTable();
        EmailSettingsDT = GetEmailSettings();
        if (EmailSettingsDT.Rows.Count > 0)
        {
            string a = EmailSettingsDT.Rows[0]["SMTPHost"].ToString();
            int port = Convert.ToInt32(EmailSettingsDT.Rows[0]["SMTPPort"]);
            using (SmtpClient smtp = new SmtpClient(EmailSettingsDT.Rows[0]["SMTPHost"].ToString()))
            {

                var basicCredential = new NetworkCredential(EmailSettingsDT.Rows[0]["SMTPUsername"].ToString(),EmailSettingsDT.Rows[0]["SMTPPassword"].ToString());
                smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
                smtp.EnableSsl = Convert.ToBoolean(EmailSettingsDT.Rows[0]["IS_SSL"].ToString());
                smtp.UseDefaultCredentials = false;
                smtp.Credentials = basicCredential;
                smtp.Port = Convert.ToInt32(EmailSettingsDT.Rows[0]["SMTPPort"].ToString());
                var mail = new MailMessage();
                mail.From = new MailAddress(EmailSettingsDT.Rows[0]["SMTPUsername"].ToString(),EmailSettingsDT.Rows[0]["displayName"].ToString());
                mail.To.Add(Mailto);
                if (copy == true)
                {
                    mail.CC.Add(CC);

                }
                mail.IsBodyHtml = true;
                mail.Subject = Subject;
                mail.Body = Body;
                smtp.Send(mail);
                mail.dispose();
                smtp.dispose();
            }
            //var smtp = new SmtpClient(EmailSettingsDT.Rows[0]["SMTPHost"].ToString());

        }
    }
SMTP PORT:587,HOST:smtp.gmail.com

我的角度代码是：

UpdateClientReviewCandidateStatus(Data: any) {
const header = new Headers({ 'Content-type': 'application/json' });  
return this._http.post(this.apiUrl + 'ClientCandidateBulkStatusUpdate',Data,httpOptions).pipe(map((data: Response) => <any>data))

}

我尝试使用注释代码也仍然没有解决问题。 SMTP 限制发送 100 封电子邮件。我还没有达到限制，但它在发送批量电子邮件时仍在抛出。 一些电子邮件，如 5 或 10 正在发送，但其他电子邮件结构会出现上述 CORS 错误。 我也尝试使用 MailKit 和 MailChimp 发送邮件，但没有找到解决方案。 请问谁能帮我解决这个错误。

提前致谢。