Subscribe-Controller.cs

using Microsoft.AspNetCore.Mvc;
using System.ComponentModel.DataAnnotations;

namespace WebApplication2
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var builder = WebApplication.CreateBuilder(args);
            // Only add essential controller services
            builder.Services.AddControllers();
            // Add services to the container.
            builder.Services.AddRazorPages();

            var app = builder.Build();

            // Configure the HTTP request pipeline.
            if (!app.Environment.IsDevelopment())
            {
                app.UseExceptionHandler("/Error");
            }
            app.UseStaticFiles();

            app.UseRouting();

            app.MapRazorPages();
            app.MapControllers();
            app.Run();
        }
    }


    [Route("subscribe")]
    public class SubscribeController : ControllerBase
    {
        [HttpGet]
        public IActionResult Subscribe(EmailRequest data)
        {
            return Ok();
        }
    }

    public class EmailRequest
    {
        [Required]
        [EmailAddress]
        public string Email { get; set; }
    }

}
}