Function works even if I refresh the page.

I'm curious to know what was your technical solution to achieve this. If its HostedService or BackGround Service, please confirm whether this has been registed in Starup.cs or in Program.cs depends on your .NET Version you are following

Develop a background service class that handles email sending asynchronously and then Register the background service in the Startup.cs using AddHostedService. Post that Implement the ExecuteAsync method in the background service to send emails periodically.In your Razor Page's code-behind, initiate the background service when users click the email send button

To achieve background processing for sending bulk emails in an ASP.NET Core Razor Pages application, you can use a combination of background tasks and asynchronous programming. One popular approach is to use the built-in BackgroundService class along with a message queue system like RabbitMQ or Azure Service Bus. However, for simplicity, I'll demonstrate using the IHostedService interface and a hosted service background task.

Hello Sunny,

You can use here the Azure service bus or Rabbit MQ concepts like Publisher and Subscriber.

When you have clicked on the button that time you need to publish the messages.

Another side Azure functions have to consume the message of whatever you have published and inside that you need to decorate the email body and everything rest things required to send the email and send the mail to the users.

Sir it's not working.

Create a new class that inherits from BackgroundService. This class will contain the logic for sending the emails. Let's call it "EmailSenderService.cs":

using Microsoft.Extensions.Hosting;
using System;
using System.Threading;
using System.Threading.Tasks;

public class EmailSenderService : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        // Your email sending logic goes here
        while (!stoppingToken.IsCancellationRequested)
        {
            // Send emails to users
            await SendBulkEmails();

            // Wait for a certain interval before sending the next batch of emails
            await Task.Delay(TimeSpan.FromMinutes(10), stoppingToken);
        }
    }

    private async Task SendBulkEmails()
    {
        // Retrieve the list of users from the database
        List users = GetUsersFromDatabase();

        // Loop through the users and send emails
        foreach (User user in users)
        {
            // Send email to user
            await SendEmail(user.Email, "Subject", "Message");
        }
    }

    private List GetUsersFromDatabase()
    {
        // Retrieve the list of users from the database
        // Implement the logic to fetch the users from the database and return them as a list
    }

    private async Task SendEmail(string email, string subject, string message)
    {
        // Implement the logic to send an email to the specified email address
    }
}

In your Razor Page or Controller, inject the IHostedService interface and start the email sender service when the button is clicked.

public class IndexModel : PageModel
{
    private readonly IHostedService _emailSenderService;

    public IndexModel(IHostedService emailSenderService)
    {
        _emailSenderService = emailSenderService;
    }

    public async Task OnPostSendEmailsAsync()
    {
        // Start the email sender service
        await _emailSenderService.StartAsync(default);

        // Return a response indicating that the emails are being sent in the background
        return Content("Emails are being sent in the background.");
    }
}