unable to cancel a scheduled mail in sendgrid

Question

I want to send an email at a specified time in Sendgrid. according to this document.and this question,I created a sample console application in VS2022 with c#

There is no problem sending Email. However, Email is still delivered to target even after canceling

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using SendGrid;

using SendGrid.Helpers.Mail;

namespace sendmailtest
{
    internal class Program
    {
        private static string batchId = "";
        private static string apikey = "my sendgrid apikey";

        static void Main(string[] args)
        {

            SendEmail().Wait();

            Console.WriteLine("Cancel scheduled emails. yes or not?");
            var result = Console.ReadLine();
            if (result == "yes")
            {   //Cancel scheduled sends while inputting "yes" in console
                NotSendEmail().Wait();
            }
        }
        static async Task SendEmail()
        {
            var client = new SendGridClient(apikey);

            var response = await client.RequestAsync(method: SendGridClient.Method.POST, urlPath: "mail/batch");
            if (response.StatusCode == HttpStatusCode.Created)
            { // get batchID
                JObject joResponse = JObject.Parse(response.Body.ReadAsStringAsync().Result);
                batchId = (((Newtonsoft.Json.Linq.JValue)joResponse["batch_id"]).Value).ToString();
            }

            var dtNow = DateTime.Now;

            //Automatically send emails 30 seconds after execution starts
            var dtSend = dtNow.AddSeconds(30); 
            long sendAtUnixTime = new DateTimeOffset(dtSend).ToUnixTimeSeconds();

            var msg = new SendGridMessage()
            {
                From = new EmailAddress("info@sample.com", "sample"),
                Subject = "scheduling sending mail test",
                PlainTextContent = "and easy to do anywhere, even with C#",
                HtmlContent = "<strong>and easy to do anywhere, even with C#</strong>",
                BatchId = batchId,
                SendAt = sendAtUnixTime

            };
            msg.AddTo(new EmailAddress("targetEmailAddress", "targetName"));

            await client.SendEmailAsync(msg);
            //Email sent successfully

        }
        static async Task NotSendEmail()
        {
            var client = new SendGridClient(apikey);

            string data = "{\"batch_id\":\"" + batchId + "\",\"status\": \"cancel\"}";

            await client.RequestAsync(method: SendGridClient.Method.POST, urlPath: "user/scheduled_sends", requestBody: data);
        }
    }
}

How can achieve this problem. Please provide the solutions for it. Thanks in advance.

Answer 1

ToUnixTimeSeconds is based on UTC. Your dtNow is in local time. If you set it with DateTime.UtcNow you've probably fixed the issue, assuming you're living in a country with a negative timezone (as such it's probably sending the email as soon as you create the call since the scheduled date is surpassed).

https://learn.microsoft.com/en-us/dotnet/api/system.datetimeoffset.tounixtimeseconds?view=net-7.0

Going by the example of https://docs.sendgrid.com/for-developers/sending-email/stopping-a-scheduled-send your code seems fine otherwise.